ecryptfs-recover-private lacks backward compatibility
Here's how I come across this issue:
1. On an Ubuntu 14.04 amd64 system, create a new user with encrypted home dir
2. Backup the system to a separate disk
3. Do a fresh install of Ubuntu 16.10 amd64 on the same machine
4. On Ubuntu 16.10, mount the backup disk and run ecryptfs-
5. Getting this error after entering the correct LOGIN passphrase:
INFO: Found [/mnt/backup_
Try to recover this directory? [Y/n]: Y
INFO: Found your wrapped-passphrase
Do you know your LOGIN passphrase? [Y/n] Y
INFO: Enter your LOGIN passphrase...
Inserted auth tok with sig [00d89ae708c936af] into the user session keyring
mount: mount(2) failed: /tmp/ecryptfs.
ERROR: Failed to mount private data at [/tmp/ecryptfs.
I've verified the backup is fine by executing the same command on a VM running Ubuntu 14.04 live CD. All files copied successfully on the VM.