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Wikipedia:WikiProject Check Wikipedia/List of errors
< Wikipedia:WikiProject Check Wikipedia
 Check Wikipedia Toolforge List of Errors Discussion
Data for the list is compiled from the following locations: WPCleanerAutoWikiBrowserAuto-Formatter.
  Fixes all cases    Warns of an error and fixes some cases    Warns of an error
Quick link templates
Targetuseexample
this list
{{CW|##}}
{{CW|50}}
CW Error #50
the CheckWiki report
{{Checkwiki|##}}
{{Checkwiki|50}}
CW Error #50
#PriorityCosmeticErrorWPCAWBAFTypeReason
01
(dump)
LowYesTemplate contains useless word template:
Syntax errorArticle contains a template that includes the redundant prefix "template:" (eg. {{Template:reflist}}). Removing it is usually useful when copying page in another Wikipedia.
02
(dump)
HighSometimes<br>, <center> or <small> tag with incorrect syntax. Cases of <span /> and <div />.
Syntax errorA <br> or <br /> tag (note the slash) are the only standard formats. See the HTML standard for <br> or <small>.
Mediawiki's Tidy tool will be replaced which may cause many now valid tags, such as </br> and <center />, to no longer work.
03
(dump)
HighNoReference list missing
Display problemThe article contains one or more <ref> tags, but is missing a {{Reflist}} or <references /> tag
04
(dump)
MidNoHTML text style element <a>
Display problemsThe article contains one or more <a> tags. <a> tags will not show up in the rendered article and should use normal wikilink code for external links.
05
(dump)
HighNoComment tag with no correct end
Display problemMissing closing comment tag. <!-- -->
06
LowNoDEFAULTSORT with special characters
Syntax errorDon't use special lettering in DEFAULTSORT
07
(dump)
MidNoHeadlines all start with three "="
AccessibilityFirst headline starts with "=== XY ===". It should be "== XY ==" header. This causes organisational and accessibility problems.
08
(dump)
HighNoHeadline should end with "="
Display problemHeadline should end with "=".
09
(dump)
LowYesCategories multiple in one line
Against conventionTwo or more categories in one line.
10
HighNoSquare brackets with no correct end
Display problemFound a "[[" brackets with no corresponding "]]" brackets.
11
OffYesHTML named entities
Source readabilityHTML code found where a Unicode character could be used. For example, &auml; used instead of ä. It is difficult to comprehend for beginners.
12
Low?HTML list elements
Source readabilityDetection <ol>, <ul>...</ul> or <li> tags. Sometimes it is necessary to have these tags, especially in infoboxes.
13
(dump)
HighNo<math> tag without correct match
Display problemMissing </math> or <math> tag.
14
(dump)
HighNo<source> tag without correct match
Display problemMissing </source> or <source> tag.
15
(dump)
HighNo<code> tag without correct match
Display problemMissing </code> or <code> tag.
16
(dump)
LowYes[a]Unicode control characters
Incident detectionDetection of Unicode controls such as 0+FEFF, 0+200E, 0+200B and PUA characters.
17
(dump)
LowYes[a]Category duplication
Incident detectionUnnecessary duplicate categories found.
18
OffYesCategory's first letter is small
Against conventionAgainst convention. If turned on again, check if CamelCase cases (e.g. Category:iPhone) have consensus to be changed to
19
(dump)
HighNoHeadlines start with one "="
AccessibilityA heading section starts with just one "=". This causes organisational and accessibility problems
20
(dump)
LowYesSymbol for dead
Source readabilityThe article had a &dagger; and not †
21
OffNoCategory: in English
Incident detection[[Category: ]] found when the native language should be used
22
OffYesCategory with space
Against conventionCategory contains an unnecessary space, for example: [[ Category:ABC]] or [[Category : ABC]].
23
(dump)
HighNo<nowiki> without correct match
Display problemMissing </nowiki> or <nowiki> tag.
24
(dump)
HighNo<pre> without correct match
Display problemMissing </pre> or <pre> tag.
25
(dump)
MidNoHeadline hierarchy
AccessibilityAfter a section headline "==", there should not be a headline of "====". This causes organisational and accessibility problems.
26
(dump)
LowYesHTML text style element <b> (bold)
Accessibility
Source readability
Found a <b> tag. Should use wiki markup of '''. See WP:Deviations
27
OffYesUnicode syntax
Source readability&#169; gives very little clue as to what this is supposed to be. Use &copy; or the symbol directly ©. Some entries, like the [ ] brackets should remain in unicode, or converted to {{!(}} and {{!)}} when used in external links.
28
(dump)
HighNoTable with no correct end
Display problemAn opening table has "{|" tag, but no corresponding closing "|}" tag.
29
(dump)
HighNo<gallery> without correct match
Display problemMissing </gallery> or <gallery> tag.
30
OffNoImage without alternate description
Accessibility
31
Low?HTML table element
Source readabilityA <table>, <tr> or <td> tag was found. Should use wiki markup instead.
32
HighNoDouble pipe in a link
Display problemArticle contains a wikilink like [[text|text2|text3]] (displays as text2|text3), [[text||text3]] or [[text|text2||]]. or a broken wikilink inside a table.
33
Off?HTML text style element <u> (underline)
Against convention
34
HighNoTemplate programming element
Syntax errorA template programming element, such as {{{1}}}, #if or #switch, was found. They are usually not needed or a regular template can be substituted instead.
35
OffNoImage gallery without description
Accessibility
36
LowNoRedirect with incorrect syntax
Display problemRedirect will not work
37
LowNoDEFAULTSORT missing for titles with special letters
Display problemDon't use special lettering for sorting. DEFAULTSORT should be set without the special lettering.
38
(dump)
LowYesHTML text style element <i> (italics)
Accessibility
Source readability
Found a <i> tag. Should use wiki markup of ''. See WP:Deviations
39
LowNoHTML text style element <p>
AccessibilityFound a <p> tag. Usually should use wiki markup's blank line. Some tags, such as <ref> must use <p> due to a wikimedia bug.
40
Low?HTML text style element <font>
Against conventionFound a <font> tag. This tag isn't used in HTML5
41
Off?HTML text style element <big>
Against conventionFound a <big> tag. This tag isn't used in HTML5
42
(dump)
Low?HTML text style element <strike>
AccessibilityFound a <strike> tag. This tag isn't used in HTML5. Use <s> instead. However, strikes shouldn't be used at all for accessibility reasons, so removing the strike is usually the best option.
43
HighNoTemplate with no correct end
Display problemFound a "{{" brackets with no corresponding "}}" brackets.
44
LowNoHeadlines with bold
Against conventionA headline is all or partially bold. This should rarely be used and may or not be bold depending on the browser used.
45
LowNoInterwiki duplication
Display problemDuplicate entry. Now that interwiki links have been moved to wikidata, this error is possibly due to wikilinks that ought to be rendered that omits the leading : in [[:pt:Jorge de Mascarenhas]]. Should often be converted to internal redlinks per WP:BUILD/WP:REDLINK.
46
HighNoSquare brackets without correct beginning
Display problemA broken wikilink was found.
47
HighNoTemplate without correct beginning
Display problemFound a "}}" brackets with no corresponding "{{" brackets.
48
(dump)
LowNoTitle linked in text
Display problemA wikilink of the article's title was found. This creates an unnecessary circular wikilink per MOS:OVERLINK​/​WP:SELFREDIRECT and inappropriately bolds the linked word.
49
HighNoHeadline with HTML
Accessibility
Source readability
Found a headline created with HTML tags <h1>, <h2>, etc. per MOS:DEVIATIONS and MOS:HEAD.
50
OffYesen dash or em dash
51
MidNoInterwiki before last headline
Syntax errorWith interwikis no long used, this usually means a syntax problem with a interlanguage link, ie [[de:foo]] instead of [[:de:foo]]
52
LowYesCategory before last headline
Against conventionCategories should be placed in the last section. If a link is intentional, used [[:Category:Foobar]]
53
MidNoInterwiki before last category
Syntax errorWith interwikis no long used, this usually means a syntax problem with a interlanguage link, ie [[de:foo]] instead of [[:de:foo]]
54
(dump)
LowNoBreak in list
AccessibilityWP:LISTGAP
55
(dump)
LowNoDouble <small> tags
AccessibilityCauses the text to be smaller than 85%. This goes against accessibility guidelines.
56
OffNoArrow as ASCII art
The article had an arrow like "<--" or "-->" or "<==" or "==>". Write better this arrow with the Unicode "←" or "→" or "⇐" or "⇒".
57
LowNoHeadlines end with a colon
Against conventionRemove the :
58
MidNoHeadline all CAPS
Against conventionHeadlines should normally use sentence case, unless referring to titles of works and all-caps acronyms.
59
LowNoTemplate value ends with a <br>
Syntax errorCauses whitespace errors
60
HighNoTemplate parameter with a problem
Syntax errorUsually means a broken wikilink inside a template. Can also mean the '=' sign is missing and replaced with another character.
61
LowNoReference before punctuation
Display problem<ref> comes after not before various punctuation marks (.,?:;!);
62
HighNoURL without http://
Syntax errorA URL was found that contained no http://. Example: [en.wikipedia.org Wikipedia]
63
LowNo<small> in a <ref>, <sub> or <sup>
Accessibility<ref> and <sub> tags already create smaller text. Adding a <small> would cause the text to be smaller than 85%. This goes against accessibility guidelines.
64
(dump)
LowYesLink equal to linktext
Syntax errorFinds cases of [[Foo|Foo]]. A Visual Editor bug causes wikilinks with italics or bold to be done incorrectly, usually some text outside the wikilink will also be bold or italized. Moreover, WP:NOPIPEDLINK.
65
LowYesImage description ends with <br>
Syntax errorClutter/Does nothing
66
LowNoImage description with full <small>
AccessibilityImage description text is already smaller. Adding a <small> would cause the text to be smaller than 85%. This goes against accessibility guidelines.
67
OffNoReference after punctuation (see 61 instead)
68
OffNoLink to other language
69
(dump)
MidNoISBN with incorrect syntax
Incorrect contentPer WP:ISBN, the correct format is ISBN 978-2345-78383-1. Also finds ISBNs inside external links as Wikimagick doesn't work and ISBN template can cause problems.
70
(dump)
MidNoISBN with wrong length
Incorrect contentISBNs should have a length of 10 or 13 characters
71
(dump)
MidNoISBN with wrong position of X
Incorrect contentX is only allowed in the last position of the ISBN
72
(dump)
MidNoISBN-10 with wrong checksum
Incorrect contentISBN checksum is wrong, verify the ISBN
73
(dump)
MidNoISBN-13 with wrong checksum
Incorrect contentISBN checksum is wrong, verify the ISBN
74
HighNoLink with no target
Against convention
Incorrect content
[[|foobar]] links to foobar. The pipe is either unneeded, someone forgot to give a target, or someone vandalized the article.
75
Off?Indented list
76
Low?Link with encoded space
Source readabilityFound a URI encoded space, ie %20, inside a wikilink. This usually indicates a badly constructed external link.
77
OffNoImage description with partial <small>
78
LowNoReference list duplication
Display problemFound two or more {{reflist}} or <references /> tags
79
OffNoExternal link without description
80
HighNoExternal link with a line break
Display problemFound a newline character inside an external link or a missing closing bracket. A newline character causes the link not to work.
81
Off?Reference duplication
Saves wikitext, and makes it easier to maintain the article, as you will only need to change one entry to update multiple instances of the same reference
82
Off?Link to other wikiproject
83
(dump)
MidNoHeadlines start with three "=" and later with two "="
Accessibilityorganisational and accessibility problems.
84
OffNoSection without content
85
Low?Tags without content
Source readabilityAn empty <ref></ref> or <span></span> serves no purpose. This can be confusing to editors, and lead to issues if someone interacts with the empty tags by mistake.
86
HighNoExternal link with two brackets
Display problemFound an external links surround by double brackets.
Example: [[http://www.wikipedia.org Wikipedia]]
87
OffNoHTML named entities without semicolon
Display problem
88
LowYesDEFAULTSORT with a blank at first position
Against conventionThe space in {{DEFAULTSORT: DuBois, Lewis}} is useless and ignored by MediaWiki.
89
LowNoDEFAULTSORT with no space after the comma
Syntax errorThe script found a DEFAULTSORT without a space after the comma {{DEFAULTSORT:DuBois,Lewis}}. The causes the article to be sorted as the first DuBois article.
90
MidNoInternal link written as an external link
Syntax errorThe script found an external link that should be replaced with a wikilink. An example would be on enwiki [http://en.wikipedia.org/wiki/Larry_Wall Larry Wall] should be written as [[Larry Wall]].
91
MidNoInterwiki link written as an external link
Syntax errorThe script found an external link that should be replaced with an interwiki link. An example would be on enwiki [http://fr.wikipedia.org/wiki/Larry_Wall Larry Wall] should be written as [[:fr:Larry Wall]].
92
(dump)
OffNoHeadline double
AccessibilityThis causes navigation and accessibility issues
93
MidNoExternal link with double http://
Syntax errorThe script found an external link that had double http://. An example would be [http://http://www.google.com]
94
MidNoReference tags with no correct match
Display problemA <ref> or </ref> tag was found without the corresponding beginning or ending tag.
95
LowNoEditor's signature or link to user or draft space
Syntax errorSee Wikipedia:UPYES and WP:SIGNHERE
96
MidNoTable of Contents after first headline
AccessibilityTOC should be placed at the end of the lead section of the text, before the first section heading. Users of screen readers do not expect any text between the TOC and the first heading. See WP:TOC.
97
MidNoTOC has material after it and before the first headline
AccessibilityScreen readers don't process material that comes between the Table of Contents and first headline. See WP:TOC.
98
(dump)
HighNo<sub> with no correct end
Display problemMissing </sub> tag. Can cause display problems in Visual Editor and mw:Html5Depurate
99
(dump)
HighNo<sup> with no correct end
Display problemMissing </sup> tag. Can cause display problems in Visual Editor and mw:Html5Depurate
100
(dump)
Low?List tag with no correct match
Source readabilityList tag (<ol>, <ul> or <li>) with no correct match.
101
(dump)
LowNoOrdinal number found inside <sup> tags
Against conventionOrdinal numbers should be in regular text, not inside <sup> tags See MOS:ORDINAL.
102
(dump)
MidNoPMID with incorrect syntax
Incorrect contentPer WP:PMID, the syntax should be PMID 4957203 Also checks if PMID is inside an external link as Magiclinks and {{PMID}} template won't work.
103
(dump)
MidNoPipe Template inside a wikilink
Syntax errorThe magic word {{!}} shouldn't be used inside a wikilink. | should be used instead.
104
(dump)
MidNoUnbalanced quotes in ref name
Syntax errorThe script found unbalanced quotes in a reference tag. For example <ref name="ref 1>
105
(dump)
HighNoHeading should begin with "="
Display problemA heading should begin with a "=".
106
(dump)
MidNoISSN with incorrect syntax
Display problemThe script found a problem with ISSN syntax. A normal ISSN looks like ISSN 3895-2372 or 3957-957X. There must be a - between the numbers (don't use dashes). Best if {{ISSN}} template is added. Also finds cases where the ISSN is inside an external linkss
107
(dump)
MidNoISSN with wrong length
Incorrect contentThe script checked the ISSN and found it not containing 8 characters. ISSN should have 8 characters.
108
(dump)
MidNoISSN with wrong checksum
Incorrect contentThe script checked the ISSN and found a problem with the checksum in the ISSN. Also see Category:Articles with invalid ISSNs.
109
(dump)
HighNoInclude tag error
Display problemThe script found a problem with opening or closing tags for <includeonly>, <onlyinclude> or <noinclude> tags. This can cause transclusion problems.
110
OffNoInclude tag found
Display problemThe script found a <includeonly>, <onlyinclude> or <noinclude> tags.
111
(dump)
OffNoRef after last reference list
Display problemThere are <ref> tags, after the {{reflist}} or <references> tags.
112
Low?Bad or deprecated css attributes
Display problemBad CSS should be fixed. Deprecated values should be updated for modern rendering.
113
LowNoNewline inside a wikilinkDisplay problemFound a newline character inside a wikilink. A newline character causes the wikilink not to work.
Note: errors starting at #500 are not detected by CheckWiki, but only by WPC.
501
BotNoSpelling and typography
Proposals for fixing spelling and typography based on suggestions.
502
OffYesTemplate namespace in template usage
Replaced by CW Error #1
503
OffNoInternal link in title
504
(dump)
OffNoReference in title
505
OffNoImage without alternative description
506
OffNoReference with a numeric name
507
OffNoGallery without caption
508
OffNoMissing template
509
OffYesInternal link could be compacted
510
OffNoNon working pipe trick
511
OffNoInternal link written as external link
Replaced by CW Error #90
512
OffNoInterwiki link written as external link
Replaced by CW Error #91
513
(dump)
OffNoInternal link inside external link
An external links contains an internal link, see Special:LintErrors/wikilink-in-extlink
514
OffNoMissing named reference
515
Off?Title linked in text through redirect link
516
OffYes<br /> tags in main namespace
517
Off?strike tags
Replaced by CW Error #42
518
Bot?nowiki tags in main namespace
nowiki tags are often not needed in main namespace
519
Off?a tags in main namespace
Replaced by CW Error #4
520
Off?Weird characters (pawns, snowmen) in main namespace
521
Bot?Date format in templates
522
Off?Empty title
An empty title (like == <nowiki /> ==) has been detected.
523
Off?Duplicate image
524
Low?Duplicate arguments in template calls
See Category:Pages using duplicate arguments in template calls
525
Off?Span tag
526
(dump)
Off?Incorrect date link
Incorrect link to a date, like [[1985|2005]]
527
Low?Reference with different content
Reference tags have the same name but different content, see Category:Pages with duplicate reference names
528
Off?PMID magic link
PMID magic links will be removed from MW, see Category:Pages using PMID magic links
529
Off?ISBN magic link
ISBN magic links will be removed from MW, see Category:Pages using ISBN magic links
530
Off?RFC magic link
RFC magic links will be removed from MW, see Category:Pages using RFC magic links
531
Off?Reference inside reference
Reference tags have been found inside an other reference tag
532
Bot?Missing end tag
An opening tag has no matching end tag, see Special:LintErrors/missing-end-tag​.
533
Bot?Multi colon escape
A link has been created with a multi colon escape like Test, see Special:LintErrors/multi-colon-escape​.
534
Bot?Bogus image options
An image has been created with a bogus option, see Special:LintErrors/bogus-image-options​.
535
Bot?Tidy bug affecting font tags wrapping links
Tidy bug affecting font tags wrapping links, see Special:LintErrors/tidy-font-bug.
536
Bot?Tidy whitespace bug
Tidy whitespace bug, see Special:LintErrors/tidy-whitespace-bug​.
537
Bot?Unclosed quotes in heading
Unclosed quotes in heading, see Special:LintErrors/unclosed-quotes-in-heading​.
538
BotYesWhitespace characters after heading
Extra whitespace characters are present after a heading (like == Title == ).
539
Bot?Misnested tags
Misnested tags, see Special:LintErrors/misnested-tag​.
540
Bot?Missing end bold/italic
Missing end bold/italic, see Special:LintErrors/missing-end-tag​.
541
Off?Obsolete tag
Obsolete tag, see Special:LintErrors/obsolete-tag.
542
Bot?Empty ref tag
<ref> tag without any content like <ref></ref>.
543
(dump)
Bot?Pipe in external link
like [https://test.org/toto.html| toto].
544
Off?Missing end template in a pair
A template designed to be paired with another template is alone, like {{col-begin}} without {{col-end}}.
545
Low?Template with deprecated parameter
A template parameter is obsolete, like writing_credits in {{Soundtrack}}.
546
Off?Article without categories
An article doesn't have any category, except for optional maintenance categories.
547
(dump)
Off?Empty list item
A list item is empty, like *.
548
(dump)
Off?Punctuation in link
A link ends with a punctuation, which should usually be better placed after the link (like [[Test|test,]]).
549
(dump)
Off?Split link
A link is split in several parts (like [[Test|te]][[Test|st]]).
550
(dump)
Off?Link without text
A link doesn't have any text, so it's not displayed (like [[Test|<nowiki/>]]).
551
(dump)
Off?Empty line
A line is only composed of non displayed elements (like ''<nowiki/>'').
552
(dump)
Off?Template ending with }}}
A templates end with }}} instead of }}.
553
(dump)
Off?<nowiki /> after internal link
An internal link is followed by a <nowiki /> tag.
554
(dump)
Off?<nowiki /> in <gallery>...</gallery>
A <nowiki /> tag is inside a <gallery>...</gallery> tag.
555
(dump)
Off?<nowiki /> in the text
A <nowiki /> tag is in the text.
556
(dump)
Off?External link
External link in the text of the article.
557
(dump)
Off?Missing whitespace before a link
A link is just after the preceding text.
558
(dump)
Off?Duplicated reference
A reference is used several times for the same text.
559
Off?Separator between <ref /> tags
Consecutive <ref /> tags are not properly separated.
560
(dump)
Off?Duplicated attribute
A tag contains the same attribute several time.
561
Off?Redirection with target text
An internal link targets a redirection but display the name of the final target (like [[REDIRECT|TARGET]] with REDIRECT being a redirect to TARGET).
562
(dump)
Off?Consecutive <nowiki /> tags
Several <nowiki /> tags are used one after another.
563
Off?Unused parameters
A template has unused empty parameters.
564
Off?Unknown parameters
A template has unknown parameters.
565
(dump)
Off?<nowiki /> tag between bold/italic
A <nowiki /> tag is used between bold/italic.
566
Off?<abbr /> tag
Abbreviation should use templates instead of <abbr /> tag.
^ a b Technically cosmetic, however this is either deemed too much of a bad practice, or prevents future issues deemed egregious enough to warrant a deviation from WP:COSMETICBOT.
Last edited on 1 July 2021, at 10:57
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