The following items are new for Chef server 12.16.9:

- **Minor fixes for the PostgreSQL upgrade process**
- **Remove unused authorization objects from bifrost database**

## Fixes for the PostgreSQL upgrade process

Chef server 12.16.9 adds the following features to make the PostgreSQL
upgrade process easier:

- Ensures that your disk has the required space before starting the PostgreSQL upgrade
- For users with large databases, `pg_upgrade` timeout is now configurable. The default timeout has been increased to 2 hours.

## Remove unused authorization objects from bifrost database

This release adds the `chef-server-ctl cleanup-bifrost` command.
`cleanup-bifrost` removes unused authorization objects from the
authorization database (called bifrost). These unused objects can
accumulate on long-running Chef servers as a result of failed object
creation requests. For most users, the unused authorization objects do
not substantially affect the performance of Chef server; however in
certain situations it can be helpful to clean them up. This command is
primarily intended for use by Chef support.

See the [cleanup-bifrost](/ctl_chef_server/#cleanup-bifrost)
subcommand documentation for syntax examples and additional options.