Help:CS1 errors

This page describes the error messages reported by the Citation Style 1 and Template:Cs2 citations, what they mean, and how editors might resolve the errors. Category:CS1 errors is the general errors category and Category:CS1 maintenance is the general maintenance category.

Controlling error message display

Citation Style 1 and Template:Cs2 error messages are visible to all readers. Maintenance category messages remain hidden. Editors who wish to see all cs1|2 maintenance category messages can do so by updating either their common CSS page or their specific skin's CSS page (common.css and skin.css respectively) to include the following:

.citation-comment {display: inline !important;} /* show all Citation Style 1 error and maintenance messages */

Even with this css installed, older pages in the cache may not have been updated to show these error messages even though the page is listed in one of the tracking categories. A MEpedia:NULLEDIT will resolve that issue.

Editors who do not wish to see any of the cs1|2 error or maintenance category messages can hide them by updating their common or skin CSS stylesheet to include:

.citation-comment {display: none;} /* hide all Citation Style 1 error and maintenance messages */

Most common errors

• #Citation without a title of any form
• #Check date values in: |<param1>=, |<param2>=, ...
• #Bare URL without a title
• #|access-date= requires |url=
• #External link in |<param>=
• #Missing or empty |url=

|access-date= requires |url=

Help desk

The |access-date= (or its alias, |accessdate=) is the date that the online resource addressed by |url= was added to the article. If |access-date= has been included in the citation without |url= then this message appears. If the citation does not use a web link, then |access-date= is redundant and should be removed.

When the online resource has a publication or other fixed date associated with it, |access-date= is of limited value though may be useful in identifying an appropriate archived version of the resource. Without |url=, |access-date= is not considered useful.

To resolve this error, provide a value for |url= or remove |access-date=. Editors should try to determine why the citation has |access-date= without |url=. For example, the citation may never have had a |url=, or |url= may have been removed because it links to a site that violates the creator's copyright (see MEpedia:COPYLINK), or because |url= was deemed to be dead and (mistakenly) removed. If the citation never had |url= or it was removed for copyright violations, remove |access-date=. When a dead |url= has been removed, restore the |url= and if possible repair it (see MEpedia:LINKROT).

Pages with this error are automatically placed in Category:Pages using citations with accessdate and no URL.

|archive-url= is malformed

Help desk

Archive.org allows a variety of urls to access snapshots of an archived page. Some of these are:

https://web.archive.org/web/YYYYMMDDhhmmss/http://www.example.com – a single snapshot; this is the preferred form for use with |archive-url=

https://web.archive.org/web/*/http://www.example.com – a wildcard search results page; useful for locating an appropriate snapshot but not appropriate in a citation

https://web.archive.org/web/201603/http://www.example.com – incomplete timestamp; archive.org returns the most recent snapshot

https://web.archive.org/save/http://www.example.com – saves a new snapshot of the current target; do not use this form

There are two forms of the basic url:

https://web.archive.org/<timestamp>/... – the old form

https://web.archive.org/web/<timestamp><flags>/... – the new form

The error message identifies the reason for the message. The reasons are:

– the archive.org url is the save command

– web/ was expected but something else was found

– the timestamp portion of the url path is not 14 digits

– the flag portion of the url path (if present; new form urls only) is not 2 lowercase letters followed by an underscore: 'id_'

– liveweb.archive.org is a deprecated form of the domain name

When the archive.org url has any of these errors, Module:Citation/CS1 does not link to archive.org and emits an appropriate error message.

To resolve this error, choose the url of an appropriate snapshot from those held at archive.org. Search for the target url.

Pages with this error are automatically placed in Category:Pages with archiveurl citation errors.

|archive-url= requires |archive-date=

Help desk

|archive-date= (or its alias, |archivedate=), identifies the date that the web resource was archived.

To resolve this error, provide a value for |archive-date=. For web resources archived at archive.org, the archival date can be found in the |archive-url=; for resources archived at webcitation.org, the cache date is included in the archive header.

Pages with this error are automatically placed in Category:Pages with archiveurl citation errors.

|archive-url= requires |url=

Help desk

A properly formatted citation that includes |archive-url= and |archive-date= requires |url=. When the citation includes |dead-url=no, the ordering of elements in the rendered citation is changed to put the original url first.

To resolve this error, provide a value for |url=. For web resources archived at archive.org, the original url can be found in the |archive-url= value; for resources archived at webcitation.org, the original url is included in the archive header.

Pages with this error are automatically placed in Category:Pages with archiveurl citation errors.

|arxiv= required

Help desk

{{cite arXiv}} requires one, but not both, of the identifier parameters |arxiv= or |eprint=.

To resolve this error, ensure that the template has |arxiv= or |eprint= with a properly constructed value.

Pages with this error are automatically placed in Category:CS1 errors: arXiv.

|chapter= ignored

Help desk

Citation Style 1 templates {{cite web}}, {{cite news}}, {{cite journal}}, {{cite press release}}, {{cite podcast}}, {{cite newsgroup}}, as well as template {{citation}} when it uses |work= or any of its aliases, do not support |chapter= or the aliases |contribution=, |entry=, |article=, or |section=.

To resolve this error:

• use a more appropriate citation template, or
• place the content of the |chapter= parameter in |title=, or
• for {{cite news}}

{{cite news}}, |department= can be used to give the name of the newspaper's section (e.g. Obituaries)

Pages with this error are automatically placed in Category:CS1 errors: chapter ignored.

Check |arxiv= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |arxiv=, a test is done to see if the arXiv identifier conforms with the arXiv identifier scheme. The identifier is checked for a valid number of digits in the article id; valid year and month values; and properly-placed hyphens, slashes, and dots.

To resolve this error, ensure that the |arxiv= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: arXiv.

Check |asin= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |asin=, a test is done to see if the ASIN identifier is contains ten upper-case alphanumeric characters without punctuation or spaces and that if the first character is numeric, that the ASIN conforms to the rules for a ten-digit ISBN.

To resolve this error, ensure that the |asin= value is correct.

If the |asin= value is correct and all-numeric, use |isbn= instead and delete any |asin-tld= parameters. Articles with CS1 citations that use |asin= with all numeric values are categorized in Category:CS1 maint: ASIN uses ISBN.

Pages with this error are automatically placed in Category:CS1 errors: ASIN.

Check |bibcode= <message>

Help desk

When Citation Style 1 and Template:Cs2 templates contain |bibcode=, a test is done to see if the bibcode identifier has the proper format. Bibcodes are expected to match these requirements:

length must be 19 characters (<message> = '')

characters in position(s): (except as specified otherwise, violations produce '' in the <message> portion of the error message):

1–4 must be digits and must represent a year in the range of 1000 – next year (<message> = '')

5 must be a letter

6–8 must be letter, ampersand, or dot (ampersand cannot directly precede a dot; &. (<message> = ''))

9 must be letter or dot

10–18 must be letter, digit, or dot

19 must be a letter or dot

To resolve this error, ensure that the |bibcode= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: bibcode.

Check |biorxiv= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |biorxiv=, a test is done to see if the bioRxiv identifier comprises six numeric characters without punctuation or spaces. A common error is to include the bioRxiv url (https://dx.doi.org/10.1101/<BIORXIV>), or the biorxiv doi (10.1101/<BIORXIV>)

To resolve this error, ensure that the |biorxiv= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: bioRxiv.

Check |citeseerx= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |citeseerx=, a test is done to see if the CiteSeerX identifier has the proper format. The expected identifier is the value assigned to the ?doi= query key in the URL of a CiteSeerX document. (This query key should not be confused with a Digital Object Identifier: it should not be input as |doi=.)

For instance, if you want to link to http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.220.7880, use |citeseerx=10.1.1.220.7880.

Pages with this error are automatically placed in Category:CS1 errors: citeseerx.

Check date values in: |<param1>=, |<param2>=, ...

Help desk

If you get the following citation error: , where citation-data-name is a specific part of the citation.

This error means that a date in the citation is not in an approved format, according to MEpedia's Manual of Style.

To resolve this error, ensure that the date is an actual date and that the date format follows the Manual of Style's guidance on dates in the named parameter. See examples of unacceptable dates and how to fix them, below. Or, some conceptual issues to look for:

• incorrectly formatted dates (e.g., 2018-06 should be changed to Jun 2018)
• impossible dates (e.g., February 29, 2011)
• |access-date= must specify a day, not just a month or year.
• misplaced, incorrect, or extraneous punctuation
• extraneous text
• hyphens or slashes instead of en dashes in date ranges (en dashes are required)
• misspelling or improper capitalization (see MOS:ALLCAPS for more detail that is not in Manual of Style's guidance on dates)
• other unacceptable date formats listed in MOS:BADDATEFORMAT
• more than one date in a date-holding parameter
• Does not handle years before 100 AD, including BCE/BC dates. Try using parameter |orig-year= instead.

See Help: Citation Style 1 for information about limitations in the CS1 citation templates' handling of date formats. The MOS section on date ranges describes how to separate dates in a date range. Do not use  , –, or {{spaced ndash}} as these corrupt the metadata. To add an en dash, use the CharInsert edit tool or see Help:How to make dashes. You may also use this one: –. A bot is often able to correct the separator, provided the overall format is unambiguous.

Future dates in |date= in CS1|2 citations are limited to current year + 1; that is, for 2024, citation dates in 2025 are acceptable but citation dates in 2026 and beyond are not.

Dates prior to 1582 are treated as Julian calendar dates. Dates from 1582 onward are treated as Gregorian calendar dates. The Julian calendar was used in some places until approximately 1923. Three Julian calendar dates in the overlap period, 29 February in the years 1700, 1800, and 1900, will cause this error message because those years are not leap years in the Gregorian calendar.

The access date (in |access-date=) is checked to ensure that it contains a full date (day, month, and year) and is between January 15, 2001 (the founding date of MEpedia) and today's date plus one day, because it represents the date that an editor viewed a web-based source to verify a statement. Because editors may be in time zones that are one day ahead of the UTC date, one extra day is accepted.

Pages with this error are automatically placed in Category:CS1 errors: dates.

Examples of unacceptable dates and how to fix them

Issue	Unacceptable	Acceptable
Hyphen in date range (use en dash)	date=2002-2003	date=2002–2003
Slash in date range (use en dash)	date=2002/2003 or |date=July/August, 2003	date=2002–2003 or |date=July–August 2003
Hyphen in date range (use en dash)	date=April-May 2004	date=April–May 2004
Missing space around en dash for range of full dates	date=April 2003–May 2004	date=April 2003 – May 2004
Month capitalization	date=28 february 1900	date=28 February 1900
Month capitalization	date=28 FEBRUARY 1900	date=28 February 1900
Season capitalization	date=spring 2011	date=Spring 2011
Future date (typo)	date=2102	date=2012
Access date in future (see note above)	access-date=November 23, 2024	access-date=21 November, 2024
Access date impossibly far in the past (typo)	access-date=1 January 2001	access-date=1 January 2010
Access date only specifies month	access-date=January 2015	access-date=12 January 2015
Ambiguous date range or year and month	date=2002-03	|date=2002–2003 |date=March 2002
Bad abbreviation	date=Febr. 28, 1900	|date=Feb 28, 1900 |date=February 28, 1900
Nonexistent date	date=February 29, 1900
Undated	date=Undated	date=n.d.
Comma in month and year	date=February, 1900	date=February 1900
Comma in season	date=Winter, 1900–1901	date=Winter 1900–1901
Missing comma in format which requires it	date=February 28 1900	date=February 28, 1900 or |date=28 February 1900
Non-date text	date=2008, originally 2000	date=2008 |orig-year=2000
Zero-padding	date=January 04, 1987	date=January 4, 1987
Date with slashes	date=12/6/87	|date=December 6, 1987 |date=Jun 12, 1987
Two-digit year	date=87-12-06	date=1987-12-06
One-digit month or day	date=2007-3-6	date=2007-03-06
Wikified date	date=[[April 1]], [[1999]]	date=April 1, 1999
"mm-dd-yyyy" or "dd-mm-yyyy" date format	date=07-12-2009	date=7 December 2009 or |date=12 July 2009 or |date=July 12, 2009 or |date=December 7, 2009
Approximate or uncertain dates	date=circa 1970 or |date={{circa}} 1970	date=c. 1970

Check |doi= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |doi=, a test is done to see if the prefix portion of the DOI value contains the proper 10. registry identifier. Additionally, the |doi= value is checked to make sure that it does not contain spaces or en dashes and does not end with punctuation. Further validation of the DOI is not performed.

To resolve this error, ensure that the |doi= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: DOI.

Check |hdl= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |hdl=, a test is done to see if the System (hdl) value looks like a properly defined value. The |hdl= value is checked to make sure that it does not contain spaces or en dashes and does not end with punctuation. Further validation of the hdl is not performed.

To resolve this error, ensure that the |hdl= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: HDL.

Check |isbn= value

Help desk

Citation Style 1 and Template:Cs2 templates that contain |isbn= are checked to ensure that the ISBN is the proper length (ten or thirteen digits), that the ISBN uses the correct optional separators (simple space or hyphen), and that the final check digit is correct according to the ISBN specification. Only one ISBN is allowed in this field because the whole |isbn= value is included in the citation's COinS metadata. See also COinS. More than one ISBN, or characters that are not part of the ISBN, corrupt the COinS metadata.

The error message <type> indicator can be:

– ISBN is not 10 or 13 digits

– ISBN has one or more incorrect digits; look for typos and transposition

– ISBN has one or more 'digits' that is not in the allowed set appropriate to ISBN length

– 13-digit ISBNs must begin with '978' or '979'

– 10-digit ISBNs with the mis-positioned 'X' character

To resolve this error, ensure that the |isbn= value is correct, that only one ISBN is used, that the proper optional separators are used, and that no other text is included. Use the 13-digit ISBN when it is available. When a 10-digit ISBN is used, if the check digit is a lowercase 'x', change it to an uppercase 'X'.

• Do not try to resolve the error by simply recalculating the check digit. The check digit is there to check whether the main part of the number is correct. If the ISBN is failing to validate, it is likely that there is a typo in the main part of the number. In this case, recalculating the check digit results in an apparently valid ISBN that leads to the wrong source (or to nowhere).
• If you only have a 10-digit ISBN, do use the number as-is, do not try to convert it to the 13-digit form.
• If the ISBN as printed in your source is refusing to validate, do check both the front matter and the book cover for ISBNs. It is not uncommon for the ISBN to be misprinted in the front matter but correct on the cover.
• Do preview your edit and check that the new ISBN does now link to the correct source.

In very rare cases, publishers have released books with malformed ISBNs. If you are certain that a non-conforming ISBN truly corresponds to the published work, then you can add |ignore-isbn-error=true to the citation in order to suppress the error message. In many cases, books may have been reissued with a corrected ISBN. Use a corrected ISBN when possible.

Sometimes there are numbers assigned to |isbn= that appear to be legitimate – length is right, check digit is correct – but that aren't true ISBN numbers. This tool may be helpful.

Pages with this error are automatically placed in Category:CS1 errors: ISBN.

Check |ismn= value

Help desk

Citation Style 1 and Template:Cs2 templates that contain |ismn= are checked to ensure that the ISMN is the proper length (thirteen digits), that the ISMN uses the correct optional separators (simple space or hyphen), and that the final check digit is correct according to the ISMN specification. Only one ISMN is allowed in this field because the whole |ismn= value is included in the citation's COinS metadata. More than one ISMN, or characters that are not part of the ISMN, corrupt the COinS metadata.

To resolve this error, ensure that the |ismn= value is correct, that only one ISMN is used, that the proper optional separators are used, and that no other text is included. Make sure that the ISMN contains exactly 13 digits.

Pages with this error are automatically placed in Category:CS1 errors: ISMN.

Check |issn= value

Help desk

Citation Style 1 and Template:Cs2 templates that contain |issn= and/or |eissn= are checked to ensure that the ISSN is the proper length (eight digits) and that the final check digit validates according to the ISSN specification. Only one each of ISSN and eISSN is allowed in this field because the whole |issn= and |eissn= values are included in the citation's COinS] metadata. The ISSN and eISSN are always rendered as two four-digit numbers separated with a hyphen.

To resolve this error, ensure that the |issn= and |eissn= values are correct, that only one value per parameter is used, and that no other text is included (allowable characters are 0-9, X, and -). If the check-digit is a lowercase 'x', change it to an uppercase 'X'.

Pages with this error are automatically placed in Category:CS1 errors: ISSN.

Check |jfm= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |jfm=, a test is done to see if the Jahrbuch über die Fortschritte der Mathematik (jfm) identifier value looks like a properly defined value. The |jfm= identifier is checked to make sure that it has the form: nn.nnnn.nn where n is any digit 0–9. Further validation of the jfm identifier is not performed.

To resolve this error, ensure that the |jfm= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: JFM.

Check |lccn= value

Help desk

The |lccn= parameter is the Library of Congress Control Number identifier. It is checked to ensure that the identifier is the proper length and has the correct initial digits.

LCCN is a character string 8–12 characters long. The length of the LCCN dictates the character type of the initial 1–3 characters; the rightmost eight are always digits.

LCCN format description

Length	Description
8	all characters are digits
9	first character is a lower case letter
10	first two characters are either both lower case letters or both digits
11	first character is a lower case letter, second and third characters are either both lower case letters or both digits
12	first two characters are both lower case letters

Further validation is not performed.

To resolve this error, ensure that the |lccn= value is correct and that there are no other letters, punctuation, or other characters.

Pages with this error are automatically placed in Category:CS1 errors: LCCN.

Check |message-id= value

Help desk

The |message-id= parameter holds the unique identifier associated with a netnews message. The value in |message-id= is checked to make sure that it contains @ between left and right identifiers. |message-id= is also checked to make sure that the first character is not < and the last character is not >. Module:Citation/CS1 adds the uri news: to the value in |message-id=. If the value in |message-id= is wrapped in <...> characters, the link created fails.

Further validation is not performed.

To resolve this error, ensure that the |message-id= value is correct, that it contains @ and is not wrapped in <...> characters.

Pages with this error are automatically placed in Category:CS1 errors: message-id.

Check |mr= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |mr=, a test is done to see if the Mathematical Reviews identifier value looks like a properly defined value. The |mr= identifier is checked to make sure that it contains only digits and that it is no more than seven digits in length. Further validation of the mr identifier is not performed.

To resolve this error, ensure that the |mr= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: MR.

Check |oclc= value

Help desk

The |oclc= parameter is the OCLC identifier. Only a single OCLC identifier is allowed. The identifier must be in one of these forms:

1. prefix ocm followed by 8 digits
2. prefix ocn followed by 9 digits
3. prefix on followed by 10 digits
4. prefix (OCoLC) followed by a variable number of digits without leading zeros
5. 1 to 10 digits without prefix

Further validation is not performed.

To resolve this error, ensure that the |oclc= value is correct.

A tip for fixing this error: Editors sometimes place valid ISBN, LCCN, ASIN, or other identifiers in |oclc=.

Pages with this error are automatically placed in Category:CS1 errors: OCLC.

Check |ol= value

Help desk

The |ol= parameter is the Open Library identifier. The identifier is one or more digits followed by a last character that is either A (authors), M (books), or W (works). Further validation is not performed.

To resolve this error, ensure that the |ol= value is correct. Do not include "OL" in the value.

Pages with this error are automatically placed in Category:CS1 errors: OL.

Check |<param>-link= value

Help desk

These link-holding parameters and their matching title-holding parameters are combined to create a working wikilink to a related article.

|author-link=

|contributor-link=

|editor-link=

|episode-link=

|series-link=

|subject-link=

|title-link=

|translator-link=

|author=

|contributor=

|editor=

|episode=

|series=

|subject=

|title=

|translator=

(Parameters checked for this error may also be of the form |authorlink=, |authorlink1=, |author1-link=, or |author-link1=.)

This error occurs when any of these |<param>-link= parameters contain a wikilink or a URL, or they contain any of the characters not permitted in article titles per MEpedia:TITLESPECIALCHARACTERS (except _ (underscore), used as a replacement for spaces, and #, used as a fragment identifier when linking to article sections). The prohibited characters are: < > [ ] | { }.

The |<param>-link= parameter value should contain only the title of an article or a link to a section of an article. Module:Citation/CS1 checks the |<param>-link= parameter values for wikimarkup and for a URI scheme (http://, https://, the protocol relative scheme //, etc.).

This error can also be caused when there is a |<param>-link= value and the matching |<param>= parameter contains a wikilink.

To resolve this error, do one of the following:

• Ensure that the |<param>-link= value is the full name of an article (without brackets) or a section of an article, and not a link to an external web site.
• Make sure that there are no wikilinks in the matching |<param>= parameters.
• If you want to link to a URL outside of MEpedia, move the link to |url= or a similar parameter, if one is available in the template you are using.

Pages with this error are automatically placed in Category:CS1 errors: parameter link.

Check |pmc= value

Help desk

The |pmc= parameter is the PubMed Central identifier. PMCs are sequential numbers beginning at 1 and counting up. Module:Citation/CS1 checks the PMC identifier to make sure that the value is a number greater than zero and less than the id_limit set in the PMC section of Module:Citation/CS1/Configuration and that the identifier contains only digits. Further validation is not performed.

To resolve this error, ensure that the |pmc= value is correct, and that there are no letters, punctuation, or other characters. Do not include "PMC" in the value.

Pages with this error are automatically placed in Category:CS1 errors: PMC.

Check |pmid= value

Help desk

The |pmid= parameter is the PubMed identifier. PMIDs are checked to ensure that the identifier is a simple number without punctuation or spaces with a value greater than or equal to 1 and less than or equal to the id_limit set in Module:Citation/CS1/Configuration. Further validation is not performed.

To resolve this error, ensure that the |pmid= value is correct. If you find something that looks like a PMID and begins with "PMC", use |pmc= instead of |pmid=.

Pages with this error are automatically placed in Category:CS1 errors: PMID.

Check |ssrn= value

Help desk

The |ssrn= parameter is the Social Science Research Network identifier. SSRNs are checked to ensure that the identifier is a simple number without punctuation or spaces with a value greater than or equal to 100 and less than or equal to 3500000. Further validation is not performed.

To resolve this error, ensure that the |ssrn= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: SSRN.

Check |url= value

Help desk

External links in Citation Style 1 and Template:Cs2 templates are made from two parts: the title (|title=, |chapter=, etc.) and the URL (|url=, |archive-url=, |chapter-url=, |lay-summary=, etc.). The |url= parameter and other URL parameters must begin with a supported URI scheme. The URI schemes http://, https:// and the protocol relative scheme // are most commonly used; irc://, ircs://, ftp://, news:, mailto: and gopher:// are also supported.

The URL field is checked to ensure that it contains only Latin characters and does not contain spaces. The URL may be protocol relative (begins with //). If there are no spaces and the URL is not protocol relative, then the scheme must comply with RFC 3986.

Top- and second-level domain names are checked for proper form. Generally, top-level domain names must be two or more letters; second-level domain names must be two or more letters, digits, or hyphens (first and last character must be a letter or digit). Single-letter second-level domains are supported for:

all ccTLDs (the country code is not validated)

the .org TLD

certain letters of the .com TLD (q, x, z)

certain letters of the .net TLD (i, q)

Third- and subsequent-level domain names are not checked. The path portion of the URL is not checked.

To resolve this error, ensure that |url= and other URL parameters contain valid URLs. Online tools are available to internationalize URLs that are written in non-Latin scripts:

"IDN Conversion Tool". Verisign.

"IDNA Conversion tool". IDNA-converter.com.

Pages with this error are automatically placed in Category:Pages with URL errors.

Check |zbl= value

Help desk

When Citation Style 1 and Template:Cs2 templates contain |zbl=, a test is done to see if the Zentralblatt MATH identifier value looks like a properly defined value. The |zbl= identifier is checked to make sure that it has the form: nnnn.nnnnn where n is any digit 0–9. Up to three leading zeros in the first quartet may be omitted. Further validation of the zbl identifier is not performed.

To resolve this error, ensure that the |zbl= value is correct.

Pages with this error are automatically placed in Category:CS1 errors: ZBL.

Cite uses deprecated parameter |<param>

Help desk

Over time, some parameters have become obsolete or unnecessary. When this happens, the parameters are identified as deprecated. Editors are encouraged to use other parameters that accomplish the same purpose as those that have been deprecated. The CS1|2 deprecated parameters are listed in the following table, along with recommended replacement parameters. Parameter names are case-sensitive. Editors should expect that support for deprecated parameters will be withdrawn.

2 parameters

Deprecated parameter	Replace with
ASIN-tld=	asin-tld=
class=	supported only by {{cite arXiv}} – remove, or use {{cite arXiv}} if appropriate

To resolve this error, use a supported parameter.

Pages with this error are automatically placed in Category:CS1 errors: deprecated parameters.

|class= ignored

Help desk

Only used in {{cite arXiv}} templates, |class= is only appropriate when the template uses |arxiv=YYMM.NNNN or |arxiv=YYMM.NNNNN identifier formats.

To resolve this error, remove |class=.

Pages with this error are automatically placed in Category:CS1 errors: class.

|contributor= ignored

Help desk

Only used in book citations, |contributor= identifies the author of a contribution, typically an afterword, forward, introduction, preface, etc., to another (primary) author's work. This error occurs when |contributor= is used in a template that is not {{cite book}} or {{citation}} or is one of these two templates and one of the |work= parameter aliases is set.

To resolve this error, choose a more appropriate CS1 or CS2 template or remove |contributor=.

Pages with this error are automatically placed in Category:CS1 errors: contributor.

|contributor= requires |<param>=

Help desk

Only used in book citations, |contributor= identifies the author of a contribution, typically an afterword, forward, introduction, preface, etc., to another (primary) author's work. As such, the primary author is required (|author= or appropriate alias) as is the title of the contribution (|contribution=).

To resolve this error, include the book's primary author in |author1=, or |last1=, |first1=, or |vauthors= and include the contribution title in |contribution=; or remove |contributor=.

Pages with this error are automatically placed in Category:CS1 errors: contributor.

Empty citation

Help desk

A Citation Style 1 or Template:Cs2 template marked as "Empty" contains no recognizable parameter identifiers. For example, this citation is marked as "empty" even though it contains usable information:

{{cite web | http://www.foobar.com | The Foobar Bar}}

The citation is "empty" because it does not contain the necessary parameter identifiers (in this case |url= and |title=) that tell {{cite web}} how to use the information that the citation does contain.

A citation is also marked as "empty" when it contains only parameters that it doesn't recognize:

{{cite book |titolo=The Foobar Bar |anno=2015}}

This citation is empty because the Italian-language parameters |titolo= and |anno= are not recognized as valid parameter names on MEpedia.

"Empty citation" may also mean that an editor meant to use another template entirely. Perhaps the editor used {{citation}} when the intent was to use {{citation needed}} or {{quote}}.

To resolve this error, add appropriate parameter identifiers, translate foreign language parameter names to their English equivalents, or replace the CS1|2 template with a more appropriate template.

Pages with this error are automatically placed in Category:Pages with empty citations.

External link in |<param>=

Help desk

This error occurs when any of the CS1 or CS2 citation title-holding parameters – |title=, |chapter=, |publisher=, |work= or any of its aliases: |journal=, |magazine=, |newspaper=, |periodical= and |website= – hold an external link (URL). External links in these parameters corrupt the citation's metadata and can be the source of a variety of other error messages.

To resolve this error, remove the external link from the identified parameter. Consider placing the external link in a more appropriate parameter:

• for |chapter=, the URL may belong in |chapter-url=.
• for other parameters, it may belong in |url=.

Pages with this error are automatically placed in Category:CS1 errors: external links.

|firstn= missing |lastn= in Authors/Editors list

Help desk

Citation Style 1 and Template:Cs2 templates requires a |lastn= parameter for each |firstn= parameter in a citation. Author and editor lists are checked for proper last/first pairing. CS1|2 will emit this error message for the first mismatch it detects. If there are more last/first mismatches in a citation, subsequent mismatches are not detected.

There is no requirement that each |lastn= have a matching |firstn=.

The error message uses a sort of shorthand: |lastn= can refer to any of the legitimate |author= aliases in the authors list. Similarly, |lastn= refers to any of the |editor-last= aliases in the editors list.

To resolve this error, ensure that each |firstn= has a corresponding |lastn=.

Pages with this error are automatically placed in Category:CS1 errors: missing author or editor.

|format= requires |url=

Help desk

These errors occur when Citation Style 1 and Template:Cs2 templates use |format= or |...-format= without also providing a corresponding URL for |url= or |...-url=, respectively. The |format= and |...-format= parameters are used to specify the file format of a web resource (e.g. PDF, DOC, XLS, etc.). In some cases an editor may have intended to use |type= to specify a kind of document (e.g. hard cover, paperback, pamphlet, etc.) The |format= and |...-format= value is always displayed.

The list of |...-format= parameters is:

|archive-format=, |chapter-format=, |conference-format=, |contribution-format=, |event-format=, |section-format=, |transcript-format=

As of 29 November 2014, |chapter-format= is a new parameter. Citations that relied on the old, somewhat odd use of |url= and |format= may need adjustment.

To resolve this error, remove |format= or |chapter-format=; define |url= or |chapter-url=; or change |format= to |type= (or to |chapter-format= if |chapter-url= is used without |url=.

Pages with this error are automatically placed in Category:Pages using citations with format and no URL.

Invalid <param>=<value>

Help desk

To function properly, some parameters are limited to a certain set of acceptable values. This error message indicates that a parameter has been assigned a value that is not a member of the parameter's defined set of acceptable values.

Parameters with limited acceptable values

parameter	acceptable values
dead-url=	no, true, y, yes, unfit, usurped
df=	dmy, dmy-all, mdy, mdy-all, ymd, ymd-all
ignore-isbn-error=	true, y, yes
last-author-amp=
mode=	cs1, cs2
name-list-format=	vanc
nopp=	true, y, yes
no-tracking=
registration=
subscription=
url-access=	subscription, registration, limited
bibcode-access=	free
doi-access=
hdl-access=
jstor-access=
ol-access=
osti-access=

To resolve this error, use an appropriate value.

Pages with this error are automatically placed in Category:CS1 errors: invalid parameter value.

Missing |lastn= in Authors/Editors list

Help desk

So that all authors and editors are listed in a rendered citation, Citation Style 1 and Template:Cs2 templates requires n in |lastn= (and its aliases) to increment by 1 for each author or editor. This error message is emitted when there is a 'hole' in the numbering (an author list made up of |author1= and |author3= but without |author2= for example).

The test will not detect a 'hole' that is larger than 1. It is presumed that when |authorn= and |authorn+1= are both not present, then the test has reached the end of the list.

The error message uses a sort of shorthand: |lastn= can refer to any of the legitimate |author= aliases in the authors list. Similarly, |lastn= refers to any of the |editor-last= aliases in the editors list.

To resolve this error, ensure that the numbering of the |lastn= parameters increments properly.

Pages with this error are automatically placed in Category:CS1 errors: missing author or editor.

Missing or empty |title=

There are two slightly different error conditions that can arise when CS1 citations lack appropriate titles. In each case, CS1 reports this error message. The necessary resolution may vary depending on the cause of the error. The error message links to the appropriate description below.

Bare URL without a title

Help desk

If you get the following error:

This error occurs when you specify a URL or Archived Version URL, in addition to specifying the MEpedia page on the publication. If you specify an MEpedia page on the publication, you can not also specify a URL or Archived Version URL.

All Citation Style 1 and Template:Cs2 templates report this error when one of the URL-containing parameters cannot be paired with an associated title. This error may also occur when |title= cannot be linked with |url= because the citation also contains a conflicting |title-link= parameter.

URL-containing parameters and associated title parameters

URL parameters	Title parameters
archive-url=	title=
chapter-url=	chapter=, |contribution=, |entry=, |article=
conference-url=	conference=
contribution-url=	chapter=, |contribution=, |entry=, |article=
transcript-url=	transcript=
url=	title=

A unique case exists: if |pmc= has a value and |url= is omitted or empty, then |title= is linked with the same URL as the PMC.

Because URLs are ugly and generally uninformative, it is expected that editors should provide a meaningful title for each URL. In most cases this can be accomplished by using the |title= parameter.

To resolve this error, provide an appropriate title for the URL-containing parameter. In the case where |url= and |title-link= are contending for |title= you must choose which one to keep. Consider moving |url= or |title-link= to a more suitable parameter.

Pages with this error are automatically placed in Category:Pages with citations having bare URLs.

Citation without a title of any form

Help desk

If you get the error :

This error means that the citation is missing a "title". Simply provide the title in the citation to correct this error. (This error also occurs when an editor uses {{citation}} but intends to use {{citation needed}} in the source editor.)

This error occurs for Citation Style 1 and Template:Cs2 templates when all of |title=, |trans-title=, and |script-title= are omitted or left blank. At least one of these title parameters must be provided for each citation.

{{cite episode}} will show this error if |series= is omitted or left blank (even if a |title= is provided).

Sometimes this error occurs because an editor has used a CS1|2 citation as a shortened footnote when {{sfn}} or one of the {{harv}} family of templates would have been more appropriate. This error also occurs when an editor used {{citation}} but intended to use {{citation needed}}.

To resolve this error, provide a value for |title=, |trans-title=, and/or |script-title= or replace the CS1|2 template with a more appropriate template. If you are listing a periodical or an issue of a periodical in a bibliography rather than within <ref>...</ref> tags, {{List journal}} may be more appropriate.

Pages with this error are automatically placed in Category:Pages with citations lacking titles.

Missing or empty |url=

Help desk

This error message is reported by {{cite web}}, {{cite podcast}}, and {{cite mailing list}} when the template parameters |url= and |archive-url= are both missing, blank or not properly entered. Note that |website= or |work= is the name of the site, not the URL.

To resolve this error, provide a value for |url= or use a more appropriate template such as {{cite book}}

{{cite book}}, {{cite journal}}

{{cite journal}} or other Citation Style 1 or Template:Cs2 template.

Pages with this error are automatically placed in Category:Pages using web citations with no URL.

More than one of |<param1>=, |<param2>=, and |<param3>= specified

Help desk

This error occurs when a Citation Style 1 or Template:Cs2 template includes more than one parameter that maps to the same meaning. For example, |author=, |last=, and |last1= are all synonyms of each other, so no more than one of these parameters should ever be used in a single template.

To resolve this error, remove or modify the redundant parameter(s).

This error occurs when a CS1 or CS2 template uses more than one type of author or editor name-list style. There are three kinds of incompatible author-name-list styles:

|authorn= and |lastn= / |firstn= (and their various aliases), |vauthors=, and |authors=

and similarly, three editor-name-list styles:

|editorn= and |editor-lastn= / |editor-firstn= (and their various aliases), |veditors=, and |editors=

To resolve this error, choose one name-list-style. Use the chosen style for both of the author and editor name-lists.

Pages with these errors are automatically placed in Category:Pages with citations having redundant parameters.

Text "????" ignored

Help desk

Unlike many MEpedia templates, the Citation Style 1 and Template:Cs2 templates do not use unnamed or positional parameters. When a citation contains text between vertical bars and that text does not contain an equal sign (=), CS1|2 ignores the text and reports the error. This is true even when the text is the name of a valid parameter.

This error can be caused by a missing vertical bar before the parameter name, e.g. | first = Chris last=Smith should be | first = Chris |last=Smith.

This error can also be caused by vertical bars that are part of URLs or titles. When vertical bars occur in URLs, replace each vertical bar with %7c. When vertical bars occur in parameter values that are not URLs, replace each vertical bar with | or {{!}}

{{!}}.

To resolve this error, remove the extraneous text, add '=', add an appropriate parameter name from the template you're using to complete the parameter, or properly encode vertical bars in URLs and titles.

Pages with this error are automatically placed in Category:Pages with citations using unnamed parameters.

|trans-<param>= requires |<param>=

Help desk

Citation Style 1 and Template:Cs2 templates report this error when the citation has an English translation of the title in |trans-title= or chapter title in |trans-chapter= but does not have the original-language title in |title= or original-language chapter title in |chapter=.

To resolve this error, provide the original language title for |title= or chapter title for |title=. Consider adding |language= if not already part of the citation.

Pages with this error are automatically placed in Category:CS1 errors: translated title.

Unknown parameter |xxxx= ignored

Help desk

Citation Style 1 and Template:Cs2 templates report this error when the name portion of a parameter's |name=value pair is not recognized as a valid name. Typically, this is caused by spelling or capitalization errors.

With the old-style citation templates, it was possible to include information within the template that was simply ignored as unrecognized parameters. The Lua-based CS1|2 engine does not ignore unrecognized parameters. The purpose of the citation is to properly identify the source; not act as a repository of notes and ancillary information.

CS1|2 template parameters are lower case. CS1|2 will report this error when the parameter's name contains uppercase letters (Xxxx, xxXx, XXXX) but the parameter's name is defined as lowercase (xxxx). The identifier parameters, like |isbn=, |pmc=, |doi=, etc., can be either lower case or upper case, but not of mixed case (|isbn= or |ISBN= but not |Isbn=). For common parameter misspellings, like |pubisher= instead of |publisher=, CS1|2 will suggest a valid parameter name.

To resolve this error, replace the erroneous parameter name with a correct one, possibly using the suggested name. Ensure that the parameter's name is correctly spelled and that there are no characters except spaces between the parameter's name and the leading vertical bar (|) or trailing equals sign (=). A list of valid parameters can be found by consulting Help:Citation Style 1 or visiting the description page of the specific template being used, such as {{cite web}}, {{cite book}}, {{cite journal}}, etc. Consider moving information associated with the unknown parameter into an appropriate parameter or to a section of the article's talk page for preservation.

Pages with this error are automatically placed in Category:Pages with citations using unsupported parameters.

Unsupported parameter(s) in cite arXiv

Help desk

{{cite arXiv}} uses a limited subset of the common Citation Style 1 parameters. This error message is emitted when parameters not in the {{cite arXiv}} subset occur in a {{cite arXiv}} template.

To resolve this error, remove the unsupported parameters. See Template:Cite arXiv for the complete list of supported parameters.

Pages with this error are automatically placed in Category:CS1 errors: arXiv.

URL–wikilink conflict

Help desk

External links in a rendered citation are a combination of url-holding parameters, |url=, |chapter-url=, etc., with title-holding parameters, |title=, |chapter=, etc. Title-holding parameters may be wikilinked to another article but not when there is a matching url-holding parameter in the citation. When this condition occurs, the wikilink is suppressed, the wiki markup ignored, and the rendered citation links to the external site.

Some templates will also cause this error if they are part of a title-holding parameter. The error occurs when the template produces wikilinked content. Templates in url-holding parameters may also corrupt the citation's COinS metadata. As a general rule, avoid using templates in title-holding parameters unless you know that the template's effects are entirely visual ({{!}} and the like).

This type of error may also occur in identifier-based templates ({{cite doi}}, etc.). When this happens, the error message is shown in the article but the error is actually located in the identifier-based citation template.

To resolve this error, remove wikilinks from title-holding parameters that are intended to be externally linked or remove the external URL, which will allow the internal wikilinks to work as expected. If wikilink-producing templates are important to the citation, move them out of the CS1 template but leave them inside the citation's <ref>...</ref> tags. Some of the functionality provided by templates may also be available through CS1 parameters.

To resolve errors in identifier-based citation templates, the template must be edited to correct the error. Exercise caution when editing these templates because identifier-based citation templates are often used in multiple articles.

Pages with this error are automatically placed in Category:CS1 errors: URL–wikilink conflict.

Vancouver style error

Help desk

This error is reported for citations that use |name-list-format=vanc. Vancouver style restricts author or editor names to the Latin alphabet. For the purposes of this test, Module:Citation/CS1 defines the Latin alphabet as the letters defined in the Unicode Latin character sets:

C0 Controls and Basic Latin (0041–005A, 0061–007A)

C1 Controls and Latin-1 Supplement (00C0–00D6, 00D8–00F6, 00F8–00FF)

Latin Extended-A (0100–017F)

Latin Extended-B (0180–01BF, 01C4–024F)

This error is also reported when a corporate or institutional author is listed in |vauthors= without proper delimiters. Corporate authors should be listed this way:

|vauthors=First Surname FM, Surname AB, ((Corporate or institutional Author)), Lastsurname XY

This error is also reported when more than two initials are used: in case of more than two initials, list only the first two.

While normally correct, sometimes the names listed on a PMID page contain errors when the author surname has a lowercase nobiliary particle. For example, PMID:17726700 lists Magnus von Knebel Doeberitz as Doeberitz Mv which is not correct. This author's name should be listed as |vauthors=von Knebel Doeberitz M.

Certain punctuation will be flagged as an error. For example, Unicode U+2019, right single quotation mark, causes an error because it is not a member of the Latin character sets identified above: |vauthors=Van’t Veer M. Replace this character with the straight (or typewriter) apostrophe: |vauthors=Van't Veer M.

To resolve this error, Romanize author and editor names. Romanizing can result in two-letter initials, for example, the Greek letter 'Θ' Romanizes to 'Th'. When author names have this kind of initial, Module:Citation/CS1 can't know if this kind of initial is a typo or a legitimate Romanized character so it will emit the Vancouver error. To suppress the error after determining that the two-character initial is correct and not a typo, treat the name as if it were a corporate name by wrapping it in doubled parentheses: |vauthors=..., Tatarinov IuS, ... → |vauthors=..., ((Tatarinov IuS)), ...

Similarly, Chinese hyphenated given names may appear in PubMed listings. For example: 'Wang Hsien-yu' may be listed on PubMed as 'Wang Hy' which will result in a Vancouver error. When this occurs, and upon verification that such names are correct, wrap them in doubled parentheses.

Pages with this error are automatically placed in Category:CS1 errors: Vancouver style.

<char> character in |<param>= at position n

Help desk

This error is reported for citations with parameter values that contain invisible or non-printable characters known as control characters; the error includes the position at which the character can be found. Module:Citation/CS1 detects parameter values that contain any of these characters:

replacement character, U+FFFD

hair space, U+200A

zero width space, U+200B

zero width joiner, U+200D (January 2018 note: text in Sinhalese reports this error due to a bug; a fix will be deployed in the first quarter of 2018)

soft hyphen, U+00AD

horizontal tab, U+0009 (HT)

line feed, U+0010 (LF)

carriage return, U+0013 (CR)

delete character, U+007F (DEL)

C0 control codes, U+0000–U+001F (NULL–US)

C1 control codes, U+0080–U+009F (XXX–APC)

To resolve invisible-character errors, remove or replace the identified character. Because these characters are mostly invisible, the error message identifies the character's position in the parameter value counted from the left. Space characters between the assignment operator (the '=' sign) and the parameter value are not counted.

Stripmarkers are special sequences of characters that MediaWiki inserts as a place-holder for certain xml-like tags. These tags include <gallery>...</gallery>, <math>...</math>, <nowiki>...</nowiki>, <pre>...</pre>, and <ref>...</ref>. The stripmarkers are replaced with content before the final page rendering. The module ignores math and nowiki stripmarkers.

To resolve stripmarker errors, remove or replace the identified tag. The error message identifies the stripmarker's position in the parameter value counted from the left. Space characters between the assignment operator (the '=' sign) and the parameter value are not counted.

Stripmarker errors can also be caused by unsupported additional text or templates in parameter values. Resolve the problem by moving the extraneous text outside of the citation template or by removing the extraneous text, as appropriate.

Pages with this error are automatically placed in Category:CS1 errors: invisible characters.

|<param>-access= requires |<param>=

Help desk

This error is reported when an access level has been specified for some external link, but the corresponding required parameter is missing or empty. The parameter can be one of

access-level specifier required parameter

specifier	required parameter
url-access=	url=
bibcode-access=	bibcode=
doi-access=	doi=
hdl-access=	hdl=
jstor-access=	jsor=
ol-access=	ol=
osti-access=	osti=

To resolve this error, either provide a value for the parameter, or remove the access level specification.

Pages with this error are automatically placed in Category:CS1 errors: param-access.