Some MediaWiki [extensions](https://www.mediawiki.org/wiki/Manual:Extensions) are missing the `license-name` field in the file `extension.json` or in `$wgExtensionCredits`. This means no license is shown for them in `Special:Version` (e.g. https://en.wikipedia.org/wiki/Special:Version) or the license is displayed as 'License', instead of something like for example `GPL-2.0-or-later`.
To fix this, we need to make changes like https://gerrit.wikimedia.org/r/#/c/264553/ in the relevant extensions.
1) Check the existing `LICENSE` or `COPYING` file of the extension to verify which license the extension has.
2) Look up the corresponding value of that license in https://spdx.org/licenses/
3) Add that value as the value of the `license-name` parameter to the file `extension.json`.
4) Provide your patch for that extension in Wikimedia Gerrit. See https://www.mediawiki.org/wiki/Gerrit/Tutorial for how to set up Git and Gerrit.
Note that some extensions are possibly missing a `LICENSE` or `COPYING` file, which would result in a broken license link.
Note: the 'extensions' listed as wikibase or data values is outside scope of this task. Most of these are actually libraries and instead need to be moved to the libraries section of SpecialVersion. (see: T123937)
**Still to do (missing a line `license-name` in the file `extension.json`) as of 2018-10-05:**
AJAXPoll
AkismetKlik
ArticleRatings
Athena
BlueSpiceSubPageTree
Cargo
CommentStreams
ConfirmEdit/MathCaptcha
ConfirmEdit/QuestyCaptcha
ConfirmEdit/ReCaptcha
ConfirmEdit/ReCaptchaNoCaptcha
ContributionTracking
Contributors
Diagnosis
DiscussionThreading
examples/ContentAction
examples/DataPages
ExternalArticles
GoogleDocTag
GoogleGeocode
GooglePlaces
HoverGallery
Hovergallery
Hreflang
LifeWebCore
LockDownEnglishPages
MagicNumberedHeadings
MarkAsHelpful
MintyDocs
MP3MediaHandler
NukeDPL
NumberOfWikis
OAuthAuthentication
OpenIDConnect
OpenLayers
PageDisqus
PageLanguage
PhpTagsWidgets
PluggableAuth
Prezi
PronunciationRecording
Push
Quantcast
QuickGV
QuickSearchLookup
SafeDelete
SearchExtraNS
SecureSessions
SemanticTitle
ShoutWikiAds
SimpleSAMLphp
SkinPerPage
Snippet
StaffEdits
StatCounter
Tabber
TestLanguageNameGrammar
Theme
TwnMainPage
UserAgreement
WhitelistPages
WikipediaExtracts