Does this work on a build older than r27042? I suspect / hope the answer is "no", since if you were encountering this class of error before, then Mafia would automatically terminate during startup. Frono's explanation makes sense, although it would still be useful if we expanded the error message to give more details (at least something that's helpful for us devs to troubleshoot what went wrong).
(Right now, if we encounter problems during startup, we discard the details of the exception and just say "we failed to grab a lock".)