We got burned by this as well. Our temp solution was to isolate the v2.1.12 tk-framework-desktopstartup and use SGTK_DESKTOP_STARTUP_LOCATION env var pointed at that folder.
I compared the location.py file in both tk-framework-desktopstartup v2.1.13 and v2.1.12 and this is the difference :
in v2.1.12 : return yaml.load(location_file) or dev_descriptor
in v2.1.13: return yaml.load(location_file, Loader=yaml.FullLoader) or dev_descriptor
From Stackoverflow : The FullLoader class is only available in PyYAML 5.1 and later.
I guess the yaml module that comes bundled with shotgrid desktop is not up to date ?
Currently working on this and can confirm that changing %APPDATA%\Shotgun\desktop\install\app_store\tk-framework-desktopstartup\v2.1.13\python\shotgun_desktop\location.py
line 71 return yaml.load(location_file, Loader=yaml.FullLoader) or dev_descriptor
to the following
try:
return yaml.load(location_file, Loader=yaml.FullLoader) or dev_descriptor
except AttributeError:
return yaml.load(location_file) or dev_descriptor
fixes the error on SG Desktop launch. Obviously directly modifying the python files inside tk-framework-desktopstartup is not advised but does seem to point to the distributed yaml inside %APPDATA%\Shotgun\desktop\install\app_store\tk-framework-desktopstartup\v2.1.13\python\tk-core\python\tank_vendor not being a supported version.