Deprecated: Use of MediaWiki\Parser\Parser::$tabsData was deprecated in MediaWiki 1.42. Called from Tabs::init in /var/www/html/extensions/Tabs/includes/Tabs.php at line 35
Topic on Extension talk:Tabs
I've found a workaround for this:
https://github.com/gbeine/mediawiki-extensions-Tabs/commit/2311b879cd86b2eb5424e0e06194e7cea98f7f74
It works for me, but I cannot give any guarantee that it covers all use cases.
Unlike this patch, there seems to be no need to patch the Parser class:
https://phabricator.wikimedia.org/rMW9bc428fe849bec872143e6d61a0d906f3e90d4f1