The Bethesda plugin has been broken for months now. Use MrJuicyBacon's fork instead.

1. Download the current build from GitHub (Code > Download ZIP).
2. Exit Galaxy if it's currently running.
3. Open the folder %LOCALAPPDATA%\GOG.com\Galaxy\plugins\installed and delete the bethesda folder.
4. Open the zip file from step 1.
5. Extract the betty folder to the installed folder in step 3.
6. Launch Galaxy and connect to Bethesda again.

This worked for me. Thanks.

Worked for me too, finally. Thank you so much.

For anyone not "in the loop" re: announcements about gaming... which is likely a lot of people...

... The issues relating to "Bethesda.net" will soon be irrelevant.

https://bethesda.net/en/article/2RXxG1y000NWupPalzLblG/sunsetting-the-bethesda-net-launcher-and-migrating-to-steam

The short version? In May, Bethesda.net will be closing down. Prior to that, users will have the means of transferring all their Bethesday games over to Steam.

Interestingly... and I had not even known this... Bethesda is now owned by Microsoft. So, this is just one more example of Microsoft closing down a service which users have committed to.

Now, in this case, I won't miss it terribly. But it's telling that, ONE MORE TIME, it's Microsoft who is behind closing down a service...