leapp upgrade fails with: Error: Undefined Model "InstalledRedHatSignedRPMReference"

Trying to upgrade from RHEL8 to RHEL9 and getting this error with the preupgrade run. No other output from the command. Ran it with the debug option and the last lines were:

...
2026-04-02 11:46:52.106 DEBUG PID: 20695 leapp.repository.system_upgrade_el8toel9: Starting actor discovery in actors/pythonthreetmpworkaround
2026-04-02 11:46:52.114 DEBUG PID: 20695 leapp.repository.common: Running actor discovery
2026-04-02 11:46:52.116 DEBUG PID: 20695 leapp.repository.system_upgrade_common: Loading workflow modules
2026-04-02 11:46:52.118 DEBUG PID: 20695 leapp.repository.system_upgrade_el8toel9: Loading workflow modules
2026-04-02 11:46:52.119 DEBUG PID: 20695 leapp.repository.common: Loading workflow modules

Error: Undefined Model "InstalledRedHatSignedRPMReference"
[root@myserver] ~ 802 ->

This system was upgraded from RHEL 7 to RHEL8 via LEAPP.