
The Moodle update process has been paused because PHP scripts from at least two major versions of Moodle have been detected in the Moodle directory.
This can cause significant problems later, so in order to continue you must ensure that the Moodle directory contains only files for a single version of Moodle.
The recommended way to clean your Moodle directory is as follows:
When you have a clean Moodle directory, refresh this page to resume the Moodle update process.
This warning is often caused by unzipping a standard Moodle package over a previous version of Moodle. While this is OK for minor upgrades, it is strongly discouraged for major Moodle upgrades.
This warning can also be caused by an incomplete checkout or update operation from the Git repository, in which case you may just have to wait for the operation to complete, or perhaps run the appropriate clean-up command and retry the operation.
You can find more information in upgrade documentation at https://docs.moodle.org/311/en_us/Upgrading.