Thread:Extension talk:Semantic MediaWiki/Cannot install core SMW2.0 extension on MW1.23/reply (2)

You can not use Semantic Bundle with any other version of SMW of which it has been released because it registers the vendor/autoloader manually and doesn't use Composer to manage its package dependencies which caused issues in the past [0, 1] and will so in future because of the different class map.

If you install SMW via Semantic Bundle then you have to wait until a new version is released otherwise trying to upgrade to another version of SMW will ultimately fail.

I would suggest you deleted the vendor folder and re-install SB.

For example, if on the other hand you install SMW via Composer, each time an update or removal occurs the autoloader (which is where the "Fatal error: Class" message comes from in case classes are not registered) is being re-generated to ensure it matches with the expected class map.

[0] https://github.com/SemanticMediaWiki/SemanticMediaWiki/issues/229 [1] http://wikimedia.7.x6.nabble.com/Installing-SMW-without-composer-tp5023207p5023218.html