Hi Marc,
I am having a very similar problem but was getting this error:
File “/Applications/PsychoPy.app/Contents/Resources/lib/python3.6/psychopy/projects/pavlovia.py”, line 1049, in getGitRoot
File “subprocess.pyc”, line 356, in check_output
File “subprocess.pyc”, line 438, in run
subprocess.CalledProcessError: Command ‘[‘git’, ‘branch’, ‘—show-current’]’ returned non-zero exit status 129.
So I used the advice to delete the userpref and appdata files given as a solution here:
https://www.psychopy.org/troubleshooting.html#cleaning-preferences-and-app-data
I have also removed old versions of Psychopy, restarted my mac then reinstalled the latest version.
However I am still getting this error.
I’m not sure what else to try. Any advice on how you deleted the previous versions of Psychopy (I made sure I deleted them and removed them from trash). My traceback is slightly different to yours so I will keep looking into it but any tips would be greatly appreciated.