On thetestwiki.org which is running MediaWiki version 1.29 - whenever a user clicks the "check syntax" button when modifying abuse filter conditions, it says "an unknown error occurred" regardless of the changes. This happens when pressing the button for a general test filter with no conditions, and for other filters where the conditions are obviously valid because the filter works. See the screenshot of the general test filter below.
Description
Description
Event Timeline
Comment Actions
https://www.mediawiki.org/wiki/Manual:How_to_debug provides some info how to potentially debug.
Comment Actions
Users global account is locked, and thus they are unable to log in here and comment on this.