Here's what always works for me to fix the open-a-project crashes: Delete the project.xcworkspace file inside the <project name>.xcodeproj bundle.Happens several times a day for me so I created an Applescript for each project that sits on my Desktop that I can activate to fix this situation.

I've discovered the command won't writing attributes either. And I just finished writing a bunch of code that depends upon setting and retrieving my own private attribute value. This could be a new security restriction. If so, using the C function calls to do this won't work either. I just tried a sudo with the command and that didn't work either with it doing nothing yet returning a zero code. Hopefully this is something we can change on an application basis in the Security & Privacy pane of System Preferences.