Not working hooks "SpecialListusersHeaderForm" and "SpecialListusersHeader" (tested on version 1.30 and 1.31). Changing the "out" variable does not add text to the Special:ListUsers page.
The problem occurs because of an error in the array names in the file UsersPager.php: https://doc.wikimedia.org/mediawiki-core/master/php/UsersPager_8php_source.html
In the lines 336 and 352 instead of the name of the array "$formDescriptor" used "$formDescript i or".
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Change 454624 had a related patch set uploaded (by Jayprakash12345; owner: Jayprakash12345):
[mediawiki/core@master] Fix typo in formDescriptor array
Caused by https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/362872/ which is in REL1_30, REL1_31
Needs backporting? Adding the tags. Remove when not needed
Change 454624 merged by jenkins-bot:
[mediawiki/core@master] Fix typo in formDescriptor array
Change 456061 had a related patch set uploaded (by Legoktm; owner: Jayprakash12345):
[mediawiki/core@REL1_31] Fix typo in formDescriptor array
Change 456062 had a related patch set uploaded (by Legoktm; owner: Jayprakash12345):
[mediawiki/core@REL1_30] UsersPager: Fix typo in formDescriptor array
Change 456061 merged by jenkins-bot:
[mediawiki/core@REL1_31] UsersPager: Fix typo in formDescriptor array
Change 456062 merged by jenkins-bot:
[mediawiki/core@REL1_30] UsersPager: Fix typo in formDescriptor array