After updating to MediaWiki 1.26.0 and also updating the CategoryTree extension I found the following in the apache error log:
[Wed Dec 16 11:05:49.239904 2015] [:error] [pid 21518] [client xxx.xxx.xx.xx:52235] PHP Warning: OutputPage::getModuleStyles: style module should define its position explicitly: ext.categoryTree.css ResourceLoaderFileModule [Called from OutputPage::getModuleStyles in /var/www/mw-test/includes/OutputPage.php at line 621] in /var/www/mw-test/includes/debug/MWDebug.php on line 300, referer: https://www.xxxxxxxxxxx.xx/mw-test/index.php/Spezial:Spezialseiten
[Wed Dec 16 11:05:49.307388 2015] [:error] [pid 21518] [client xxx.xxx.xx.xx:52235] PHP Warning: OutputPage::getModuleStyles: style module should define its position e xplicitly: ext.categoryTree.css ResourceLoaderFileModule [Called from OutputPage::getModuleStyles in /var/www/mw-test/includes/OutputPage.php at line 621] in /va r/www/mw-test/includes/debug/MWDebug.php on line 300, referer: https://www.xxxxxxxxxxx.xx/mw-test/index.php/Spezial:Spezialseiten
When researching I found other Wikis are also experiencing this problem:
http://thwiki.org/t=Kategorie:Verbesserung_n%C3%B6tig!
CategoryTree: REL1_26
2015-11-17T01:02:41
8d91b0a