If you keep getting the following warning after upgrading to Fedora 33:
warning: Found bdb Packages database while attempting sqlite backend: using bdb backend.
Try rebuilding RPM database:
If that results in:
error: can't create transaction lock on /var/lib/rpm/.rpm.lock (Permission denied)
Your selinux permissions are broken due to a bug. Use restorecon to restore them to defaults:
restorecon -Rv /var/lib/rpm
You should now be able to rebuild the RPM database: