MediaWiki 1.31 upgrade

Gamepedia upgraded to MediaWiki version 1.31 on Wednesday, November 14th 2018.

MediaWiki release notes
For a full listing of the new features, bug fixes, and other information about MediaWiki version 1.31, please see the documentation on MediaWiki. MediaWiki version 1.30 is an intermediate version included in this upgrade.

Why upgrade to 1.31?
Gamepedia is committed to bringing our communities the best wiki experience possible, both as editors and readers of wikis. This upgrade allows us to do many things such as access new features in the MediaWiki core, provide updates to popular extensions, as well as to continually protect the security of our site and users. It is our expectation that the update will go smoothly and the wikis to be up and running within a few hours of the start of maintenance. We thank you for your patience during this disruptive update period.

What happened to the Wikitext/Preview/Changes tabs in the wiki editor?
These were removed by Wikimedia: ''These features were ideas in the Usability Initiative but were never finished to the level that they would be deployed on Wikimedia wikis and have been marked as "going to be removed" for years. Now is time to act on that promise.'' *The  and   buttons located at the bottom near Save Changes can be used instead. Keyboard shortcuts can also be used to help with the removal of the tabs.

If you really want the tabs back however and your wiki has gadgets enabled, you can use the PreviewTab gadget which mostly emulates the behavior. See the Gadgets documentation for more information on how to do this.

Why is my css/template/other not displaying like it used to?
As with every MediaWiki upgrade, css selectors tend to change. See MediaWiki 1.31 upgrade/CSS changes for known issues and fixes.

Additionally, the HTML 4 based Tidy library has been replaced by a pure-PHP HTML 5 parser named RemexHtml to clean up improper wikitext in a modern and standards compliant way. If your content relied on some of the tidy fix-ups that are not being continued, they will need to be fixed. See the FAQ for more information.

I found an issue with x, how do I report it?
Gather as much information as possible and report it on the talk page.