I have deleted any PGP key on my secure card (Yubikey 5), and now I want to export the keys again.
However this fails with error message:
gpg: KEYTOCARD failed: Unusable secret key
So I deleted directory .gnupg to start all over again. Executing command
created the directory again.
Then I imported the all keys (incl. private key) from a backup.
However, the subkeys are still marked as stub, and I think this is causing the error when I try to export the keys to secure card.
Please advise how to remove the stub.