Semantic MediaWiki 3.0.0Released on 11 October 2018 and compatible with MW 1.27.0 - 1.31.x. started to use MediaWiki's extension registration mechanism 1 to load and enable its functionality. If for some reason Semantic MediaWiki was installed but not enabled, Semantic MediaWiki 3.1.0Released on 23 September 2019 and compatible with MW 1.31.0 - 1.33.x. added some visibility to the Special:Version page 2 and shows a message to remind users about a potential missing
enableSemantics function call.
If the extension was installed but deliberately not enabled (e.g. for a specific wiki in a wiki farm setup) then it is possible to use configuration parameter
$smwgIgnoreExtensionRegistrationCheckSets whether users will be informed about the discrepancy of having Semantic MediaWiki installed but not enabled to suppress the check and notification on special page "Version".