Tried previous build and this one (dl says: 2.7.4c).   Crash report pplication Specific Backtrace 1: 0 CoreFoundation 0x00007fffc96c22cb __exceptionPreprocess + 171 1 libobjc.A.dylib 0x00007fffde4dd48d objc_exception_throw + 48 2 CoreFoundation 0x00007fffc9740c3d + [NSException raise:format:] + 205 3 Foundation 0x00007fffcb07d800 - [NSString(NSPathUtilities) stringByAppendingPathExtension:] + 122 4 Sourcetree 0x0000000103d0e8d9 Sourcetree + 641241 5 Sourcetree 0x0000000103d0e5dc Sourcetree + 640476 6 libdispatch.dylib 0x00007fffded96524 _dispatch_call_block_and_release + 12 7 libdispatch.dylib 0x00007fffded8d8fc _dispatch_client_callout + 8 8 libdispatch.dylib 0x00007fffded9c196 _dispatch_queue_override_invoke + 743 9 libdispatch.dylib 0x00007fffded8f6b5 _dispatch_root_queue_drain + 476 10 libdispatch.dylib 0x00007fffded8f48c _dispatch_worker_thread3 + 99 11 libsystem_pthread.dylib 0x00007fffdefdc5a2 _pthread_wqthread + 1299 12 libsystem_pthread.dylib 0x00007fffdefdc07d start_wqthread + 13