Help:CS1 errors

This help page is a how-to guide.

It details processes or procedures of some aspect(s) of Wikipedia's norms and practices. It is not one of Wikipedia's policies or guidelines, and may reflect varying levels of consensus and vetting.

This page describes the error messages reported by the Citation Style 1 and Citation Style 2 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.

Errors issued by Wikipedia's <ref> system, in which citation templates are typically embedded, can be found at Help:Cite errors.

Controlling error message display

Preview messages

When editors preview an article, MediaWiki displays a preview message box under the Preview header. When Citation Style 1 and Citation Style 2 templates have error or maintenance messages, Module:Citation/CS1 summarizes those messages in the preview message box. Such a message box might look something like this:

This is only a preview; your changes have not yet been saved! → Go to editing area

Script warning: One or more {{cite book}} templates have maintenance messages; messages may be hidden (help).

Script warning: One or more {{cite journal}} templates have errors; messages may be hidden (help).

The summary messages have three components:

'Script warning:' – this prefix is provided by MediaWiki;
a colored (green maintenance or red error) message that identifies the type of template that has a message with a link to that template's documentation; wrapper templates with messages will show the name of the wrapped template, and;
'messages may be hidden' – the message suffix with a help link to this page.

Preview messages in the preview message box cannot be hidden. The preview message suffix 'messages may be hidden' means that the template's message(s) may not be visible. To learn how to show or hide template messages, see § Error and maintenance messages.

Error and maintenance messages

By default, Citation Style 1 and Citation Style 2 error messages are visible to all readers and maintenance messages are hidden from all readers.

To display maintenance messages in the rendered article, include the following text in your common CSS page (common.css) or your specific skin's CSS page and (skin.css).

(Note to new editors: those CSS pages are specific to you, and control your view of pages, by adding to your user account's CSS code. If you have not yet created such a page, then clicking one of the .css links above will yield a page that starts "Wikipedia does not have a user page with this exact name." Click the "Start the User:username/filename page" link, paste the text below, save the page, follow the instructions at the bottom of the new page on bypassing your browser's cache, and finally, in order to see the previously hidden maintenance messages, refresh the page you were editing earlier.)

.mw-parser-output span.cs1-maint {display: inline;} /* display Citation Style 1 maintenance messages */

To display hidden-by-default error messages:

.mw-parser-output span.cs1-hidden-error {display: inline;} /* display hidden Citation Style 1 error messages */

Even with this CSS installed, older pages in Wikipedia's cache may not have been updated to show these error messages even though the page is listed in one of the tracking categories. A null edit will resolve that issue.

To hide normally-displayed error messages:

.mw-parser-output span.cs1-visible-error {display: none;} /* hide Citation Style 1 error messages */

You can personalize the display of these messages (such as changing the color), but you will need to ask someone who knows CSS or at the technical village pump if you do not understand how.

Nota bene: these css rules are not obeyed by Navigation popups. They also do not hide script warning messages in the Preview box that begins with "This is only a preview; your changes have not yet been saved".

Properties category highlighting

Module:Citation/CS1 adds properties categories to some CS1|2 citations. Unlike errors or maintenance needs, there is no message when a properties category is added. Properties categories may be temporary or may be perpetual. Editors can use CSS to add special styling to CS1|2 template renderings that will highlight a citation that added a properties category. For example, this template uses a long volume name:

{{cite book |title=Title |date=May–Jun 2021 |volume = 1: Long volume}}

Title. Vol. 1: Long volume. May–Jun 2021.

If you add this to your CSS that citation will render with a pale yellow background:

.cs1-prop-long-vol {background: #FFC;}

Add one or more of these (with appropriate styling) to your CSS to highlight template renderings when those templates add the associated properties category:

.cs1-prop-foreign-lang-source {} – subcategories of Category:CS1 foreign language sources

.cs1-prop-foreign-lang-source-2 {} – Category:CS1 foreign language sources (ISO 639-2)

.cs1-prop-jul-greg-uncertainty {} – Category:CS1: Julian–Gregorian uncertainty

.cs1-prop-location-test {} – Category:CS1 location test‎

.cs1-prop-long-vol {} – Category:CS1: long volume value

.cs1-prop-script {} – subcategories of Category:CS1 uses foreign language script‎

.cs1-prop-tracked-param {} – subcategories of Category:CS1 tracked parameters

.cs1-prop-year-range-abbreviated {} – Category:CS1: abbreviated year range‎

Most common errors

#Cite <template> requires |<param>=, ~54k pages
#Cite uses generic name, ~34k pages
#Citation without a title of any form, ~30k pages
#Bare URL without a title, ~21k pages

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=Error: Invalid time., 2024`	`\|access-date=Okutobala 31, 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` or `\|date=1900-02-28`
Non-date text	`\|date=2008, originally 2000`	`\|date=2008` `\|orig-date=2000`
Zero-padding	`\|date=January 04, 1987`	`\|date=January 4, 1987`
Date with slashes	`\|date=12/6/87`	`\|date=December 6, 1987` or `\|date=6 December 1987` or `\|date=1987-12-06` or `\|date=12 June 1987` or `\|date=June 12, 1987` or `\|date=1987-06-12`
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` or `\|date=2009-07-12` or `\|date=2009-12-07`
Quarters	`\|date=3Q 1984` or `\|date=3rd Qtr., 1984` or `\|date=Third quarter 1984`	`\|date=Third Quarter 1984`
Named dates	`\|date=Xmas 1984` or `\|date=christmas 1984`	`\|date=Christmas 1984`
Approximate or uncertain dates	`\|date=circa 1970` or `\|date={{circa}} 1970`	`\|date=c. 1970`

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

Parameters combined to make wikilinks
Link-holding parameter	title-/name-holding parameter(s)
`\|author-link=`†	`\|author=`, `\|last=`, `\|last=` + `\|first=`
`\|contributor-link=`†	`\|contributor=`, `\|contributor-last=`, `\|contributor-last=` + `\|contributor-first=`
`\|editor-link=`†	`\|editor=`, `\|editor-last=`, `\|editor-last=` + `\|editor-first=`
`\|episode-link=`	`\|episode=`
`\|interviewer-link=`†	`\|interviewer=`, `\|interviewer-last=`, `\|interviewer-last=` + `\|interviewer-first=`
`\|series-link=`	`\|series=`
`\|subject-link=`†	`\|subject=`
`\|title-link=`	`\|title=`
`\|translator-link=`†	`\|translator=`, `\|translator-last=`, `\|translator-last=` + `\|translator-first=`
† Parameters checked for this error may also have the enumerated forms: `\|author-linkn=` or `\|authorn-link=` etc.

Deprecated CS1/CS2 parameters
Deprecated parameter	Replace with	Date
`\|lay-date=`	if the source named by these parameters is important to the Wikipedia article, create a cs1\|2 template for that source with all of the appropriate bibliographic information	2021-01-03
`\|lay-format=`
`\|lay-source=`
`\|lay-url=`
`\|transcripturl=`	`\|transcript-url=`	2022-01-22

Controlling error message display

Preview messages

Error and maintenance messages

Properties category highlighting

Most common errors

|access-date= requires |url=

|archive-url= is malformed

|archive-url= requires |archive-date=

|archive-url= requires |url=

|arxiv= required

|asin-tld= requires |asin=

|biorxiv= required

|chapter= ignored

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

Check |arxiv= value

Check |asin= value

Check |asin-tld= value

Check |bibcode= <message>

Check |biorxiv= value

Check |citeseerx= value

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

Check |doi= value

Check |hdl= value

Check |isbn= value

Check |ismn= value

Check |issn= value

Check |jfm= value

Check |jstor= value

Check |lccn= value

Check |message-id= value

Check |mr= value

Check |oclc= value

Check |ol= value

Check |osti= value

Check |<param>-link= value

Check |pmc= value

Check |pmid= value

Check |rfc= value

Check |sbn= value

Check |ssrn= value

Check |s2cid= value

Check |url= value

Check |zbl= value

Cite has empty unknown parameter: <param>

Cite <template> requires |<param>=

Cite uses deprecated parameter |<param>=

Cite uses generic name

Cite uses generic title

|citeseerx= required

|class= ignored

|contributor= ignored

|contributor= requires |<param>=

|doi-broken-date= requires |doi=

|edition= has extra text

Empty citation

Explicit use of et al.

External link in |<param>=

|<first>n= missing |<last>n=

|format= requires |url=

Invalid |display-<names>=<value>

Invalid <param>=<value>

Invalid |script-<param>=: <type>

|issue=/|number= has extra text

Italic or bold markup not allowed in: |<param>=

Missing |<name>n=

Missing or empty |title=

Bare URL without a title

Citation without a title of any form

Missing or empty |url=

Missing pipe

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

|page(s)= has extra text

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

|pmc-embargo-date= requires |pmc=

|ssrn= required

Text "????" ignored

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

Unknown parameter |<param>= ignored

URL–wikilink conflict

Vancouver style error