If downgrading and restoring from the seed phrase is your current option,
temporarily rename your wallet file so Electrum wont be able to load it automatically, that'll prevent that error.
Alternatively, you can remove the "gui_last_wallet" line in the config file.

Your wallet/config file can be found in your Electrum data directory, "wallets" fodler: electrum.readthedocs.io/en/latest/faq.html#where-is-my-wallet-file-located