Thread:Project:Support desk/Missing Namespace Tab Labels in Vector/reply (8)

If you are using UsabilityInitiative, delete it from your extensions and download the Vector extension. It has the same utility as in UsabilityInitiative; it is now just a separate extension.

If you are doing an upgrade from 1.16.x or downgrading from 1.17, make sure you have the proper Vector.php file from the version in the skins folder.