Post in forum #265727 - [Announcement] Tag categories for existing tags can no longer be changed via metatag

DiceLovesBeingBlown said:
You're lower than priviliged, so the error to change the category is expected

It changing into a character tag somehow isn't. Did you check if perhaps someone else just happened to change the type of the tag at the same time as you adding it?

As far as I know, the 500 issue was fixed for awhile.

For the second point, no. No other posts with that tag exist.