Startup hanging on Cassio

I installed the lastest core update, but now the system hangs on startup. The last error in the logs is this:

Waiting on integrations to complete setup: hassio

Earlier in the logs, I get these errors:

The system could not validate that the sqlite3 database at //config/home-assistant_v2.db was shutdown cleanly
Error setting up entry Supervisor for hassio

Between the two, integrations fail to load. I tried to restore from a backup, but I get the error:

Restoring a backup is not possible right now because the system is in freeze state.

What gives? I’m dead in the water. Please help.