error/debug/cannotdowngrade
From MoodleDocs
This error occurs when a new version of a add-on has been installed at some point and then has been replace by an older version of the same add-on.
In this scenario you need to determine what has caused this to happen:
- It might be that you've accidentally tried to install a version compatible with older versions of Moodle. In this case, check the Moodle plugins database for the correct version with your Moodle and install this
- It could also be that the plugin is defective - in this case you should try to contact the plugin author, using the Moodle forums for example.
