Thread:Project:Support desk/Update previous MW 1.16.5 to 1.17.0 throws an 500 internal server error/reply (31)

Mor2, Try changing your wiki's skin to the version of the Vector skin that ships with MW 1.17. I was able to fix the same tab problem you're seeing by switching to the Vector skin that ships with MW 1.17. (See above in this thread.)