Crashes on startup with Assert failure (6) on load with missing encryption key,

Trying to restart with a deliberately missing key - key 1 is available, key 19 isn't for a normal reboot. The failure mode blocks upgrades from working correctly again.

On main server, correctly starts when both keys available, but fails when one key is missing. No assert on development server (running same config, acting as a replication slave).

Attached is syslog showing successful shutdowns, failed starts, and working starts (the latter has both key 1 and key 19 in the file - note that the failed starts report key 1 not found, but that is in the file at all times)

Error persists after full reboot - the MariaDB instance fails to start, until both keys are provided.