Encrypted drive problem?

Short version:
Installed UB 18.04 on my wife’s laptop last night, upgrading it from Mint 18.3 by installing to the separate root partition. Now I can’t get past the login screen. Have verified password.

More details:

  • Downloaded UB 18.04 release version yesterday. Verified SHA256 on download.
  • Drive is partitioned as root, /home, and swap.
  • User name / machine name / password are identical to LM 18.3 install.
  • During new install, only root partition was formatted, but /home and swap were carefully incorporated into the new install. (I’ve done this numerous times with LM / Ubuntu / UM.
  • There were no error messages during install.

My guess is that somehow the install didn’t mesh with the encrypted drive, and since the new system didn’t generate the encryption, the encryption is keeping the login from completing.

Trying to anticipate a few more questions:

  1. Yes, if all else fails, there IS a backup – but that would spoil the learning experience of trying to fix this.
  2. No, despite having the encryption keys/passphrases for all my other machines’ drives (thank you, LastPass notes!), for some reason, I didn’t record it for my wife’s laptop.

Our marriage has survived 46+ years, so I’m sure it’ll weather this hiccup as well. However, the reputation of UM is at stake (in my wife’s eyes). I made the change because LM was starting the fray around the edges for her, and I’m upgrading the other machines (UM 17.10) this week.

Thanks in advance for your help.