As the title suggests, the bolt while holds my derailleur hanger to my frame is stripped; i.e. rounded off, so a hex wrench no longer can turn it.
The wrench slipped while I was tightening it, then continued to slip as I tried to un-do it to replace the bolt.
The bolt is tight, and will hold the hanger on fine, it's more the issue of needing to remove it if need be, for whatever reason.
So now, suggestions on how to remove and replace it, while minimising damage done to the frame?