ASSERTION FAILURE in /Library/Caches/com.apple.xbs/Sources/DVTFrameworks/DVTFrameworks-14882.2/DVTFoundation/FilePaths/DVTFilePath.m:905 Details: str should be a string, but it is nil It's happening on Xcode 11.6, 11.7. 12.0.1, 12.2 beta3. When I change constraints XCode crashes. I tried the commands above without success.