When parsing the output the dnf config-manager --dump command, there is a warning about an issue that according to the code shouldn't occur:

2025-10-09 15:16:27.211 WARNING  PID: 988 leapp.workflow.RPMUpgrade.dnf_upgrade_transaction: Cannot parse the dnf dump correctly, line:

It is probably caused by incorrectly handling empty or whitespace only lines in the output.

There are also possibly unbound variables in the same function.

A relevant excerpt of /var/log/leapp/leapp-upgrade.log is attached. It's from a CS9 -> CS10 upgrade, I didn't try to reproduce elsewhere, but its applicable on any upgrade path.