"ecryptfs_parse_options: Could not find key with description: [deadbeaf...]"

If the mount fails and the message "ecryptfs_parse_options: Could not find key with description: [deadbeaf...]" is in your system logs, then there was a problem inserting your mount key into your kernel user session keyring.

After a mount attempt, run keyctl_show. You should see something like this:

# keyctl show
Session Keyring
       -3 lswrv---------- 0 0 keyring: _uid_ses.0
        2 lswrv---------- 0 0 \_ keyring: _uid.0
892244932 lswrv---------- 0 0 \_ user: deadbeef...

Where deadbeef is the signature that corresponds with your key. If you don't see this, then there is a problem with your keyring setup.

If you su to root, be sure to initiate the session by using the - flag.

Finally, try linking your user keyring into your active session keyring:

# keyctl link @u @s