Unable to Boot Instance: "Please enter passphrase for disk Linux filesystem

Problem

An instance is unable to boot with the following printed in its console log.

None

[[0;32m  OK  [0m] Found device /dev/disk/by-label/UEFI.
[[0;32m  OK  [0m] Found device /dev/vda2.
[[0;32m  OK  [0m] Found device /dev/vda3.        
Starting Cryptography Setup for [disk_name]...        
Mounting /boot/efi...
[[0;32m  OK  [0m] Mounted /boot/efi.[0;1;39m
Please enter passphrase for disk Linux\x20filesystem ([disk_name])!

Environment

• Platform9 Managed OpenStack - All Versions

• Linux

Cause

A partition on the boot device has been encrypted.

Resolution

1. Rescue the instance.

2. Remove the offending partition(s) from /etc/fstab or otherwise decrypt the partition.

3. Un-rescue the instance.