Thread:Project:Support desk/Update previous MW 1.16.5 to 1.17.0 throws an 500 internal server error/reply (22)

Vector extension isn't compatible with 1.16 (perhaps thinking of usability intiave). Also Vector skin and vector extension are totally different.

It sounds like you forgot to upgrade the Language files (in the languages subdirectory). That would cause the issue you described above

You should try to find your apache error log (common place /var/log/apache/error_log ) the 500 error you described doesn't sound like a MediaWiki issue but more a server config problem.