You can now add captions to files on Commons. Captions are short descriptions of the file. They can be translated to all languages we use. They can't use wikitext markup.
Earlier a quoted HTML attribute had to be followed by a space. Now it doesn't. This means that some pages could look different when you save them even if you didn't edit that part of the text.
Templates with <templatestyles> could not show the difference between the live template and the sandbox version when they were tested. This has now been fixed. <templatestyles> has a new wrapper parameter now. You can use it for selectors like .mw-parser-output <wrapper parameter value> <selector from CSS page>.
When you see an edit in the recent changes feed or in the history of a page some of them have tags. Some tags are added automatically. You can also add tags manually. Tags for edits that have been added manually can be edited. This didn't work for a little while. This has now been fixed.
Users who could cause more damage to the wikis if someone took over their account have to have more secure passwords. This includes administrators and other user groups. They can't use passwords that are in a list of common passwords. Accounts with common passwords are easy to take over. The list of common passwords was made longer a few weeks ago and has a different error message. Some user groups have been added to those who can't use common passwords. This is to protect all accounts with user rights that could cause damage.
The AbuseFilter variable minor_edit has been removed. It was deprecated in 2016. Now you can't use it. You can fix the filters using it. You can find them if you use the search bar on Special:AbuseFilter.
The new version of MediaWiki will be on test wikis and MediaWiki.org from January 15 17h55min de 14 de janeiro de 2019 (UTC)