I am using QGIS 3.14.16 and I believe, I have somehow corrupted my QGIS/Python interaction.
My Problem: When I open QGIS and the status information reads "Starting Python", the application just closes. No error message, it is just gone. When I start in administrator mode however, it all works fine.
How I ruined the setup I had it running just fine after the initial installation. I then changed the PYTHONPATH and PYTHONHOME variables in QGIS to try to work on a virtual environment on my system. After restarting QGIS, it would not start again. I have not added any System or User Variables in the Windows settings.
How I tried to fix it I have uninstalled and deleted all files associated with QGIS twice now, but whenever I reinstall the problem is the same. QGIS is now installed in C:\Program Files\QGIS. I checked the file \QGIS\bin\qgis-bin.env and PYTHONHOME and PYTHONPATH look fine to me:
The content in \QGIS\bin\p3_env.bat also looks fine to me:
My research I found this unresolved Bug, which describes someone messing with PYTHONPATH and PYTHONHOME as well and consequently resulting in QGIS crashing. I believe he changed the variables not within QGIS (what I did), but within his User Environmental Variables. After deleting them, it worked for him again.
I found a similar bug here where the solution again was to delete environment variables. Again, I did not set any windows environment variables.
As I said, starting in administrator mode is possible, but this is not my preferred option. I want to make sure that my setup is well defined. Additionally I have encountered problems when working with "Actions", which might be related to this problem. Does anyone have ideas, what might cause the troubles? Any suggestions on what to try?