I keep getting:

"Cannot find any local file corresponding to "Unknown".
Would you like to specify the local file manually ?"

??

I Haven't managed to find a clear process that re-produces that bug, but I did find out that the problem is solved by deleting all breakpoints.

If anyway is expiriencing this problem, just end the current debug session, delete all breakpoints and shoot another debug session. after the "clean" one is finished, set the breakpoints that you want again, and go on.