User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36

Steps to reproduce:

I tried to import private gpg keys in the armor format in the OpenPGP Key Manager.

Actual results:

Everything works until this dialog appears (see screenshot):

title: "Add a Personal OpenPGP Key for <email>"
text: "Importing your OpenPGP Keys..." (with a spinner)

This dialog just hangs forever. It also can't be closed. Clicking on the close button somethings causes the key to appear in the OpenPGP Key Manager (in bold), but the dialog just statys in the importing stage. I also tried with my internet connection disabled in case it tried to download stuff from the internet without proper timeout set, that did not help.

I let it run for about 30 minutes, and the import never finished. It tried about 5 private keys, all created with openpgp, all failed. The only way to get stop the import is to kill Thunderbird. After restart, the keys are not there.

It seems to be the same issue as reported here: https://www.thunderbird-mail.de/forum/thread/84851-private-key-wird-nicht-importiert-endlos-schleife-beim-import/.

Expected results:

The import should finish. If there is a problem with the key, let the user know.

The same happens for private keys that were

a) Generated within your OpenPGP Manager with "Generate > New Key Pair"
b) Exported with "Backup Secret Key(s) to File"

Sounds like the same issue as bug 1656287.