Running app on MacOSX Mountain Lion: Job failed to exec(3) for weird reason: 13

Thanks to lanzz

I found out that the problem is permissions.

I used chmod +x to set the executable app under MacOS folder of the .app to make it executable and the problem is fixed.

If chmod doesn't work for you:

I was getting the same error with an .app file extracted from a zip but the chmod solution didn't help. I eventually found this page which suggested re-extracting the file from the original zip using the Archive Utility. This worked for my case.

(I had extracted it using 7-Zip on a PC and picked it up on the Mac via DropBox which presumably mangled the permissions in some manner.)