You can simply downgrade to version 2.9.3... the wallet format is only upgraded when you actually run v3.x and click the "OK" button when it warns about the wallet file upgrade.
As your version is crashing on startup with the python error, your wallet file will not have been touched. You can safely install v2.9.3 and everything will be OK.
Thank you. Downgrading to V2.9.3 worked without problem.
@LuanX3
Just use the portable version, anyway you always can open a wallet.dat on your portable version. Everything is stored in that file anyway, so I don't think you'll lose anything,
I did not find any wallet.dat in my "not partable version". But I found a wallet folder with my wallets. But they do not end with *.dat
-> confused