@nenin, can you list steps to reproduce?. Was the configuration checked in the Debug menu before trying to erase it?.
Running the devel version with gdb should give an useful backtrace.
I checked 2 outdated and erratic configs, deleted them and when I pressed OK I got this error msg.
Apropos, I have very old configs, and I found in one case at work PC that there were broken records, which C::B cannot read properly and as result I observed glitches. It will be nice to have kind of stand-alone verification utility.