Hi

We recently experienced a bug / major flaw with Moodle when attempting to upgrade. 

Once you commence the upgrade process, Moodle will check that the necessary resources etc are present, including the correct version of Maria DB. However, the issue arises where the upgrade process is initiated and then the user may only then discover that they do not have the latest required version of Maria DB. At this point, the upgrade process has initiated and there is no way to cancel and revert back to the current working version, without having backup copies of the database and Moodle data folders.

In our case, We ended up with Moodle in an unusable state and because one of our backups had failed our only option was to move all files to a new upgraded server with the latest version of MariaDB (which incidentally many servers do yet provide).

This could present real challenges for users who, for one reason or another, may not have access to a working backup, and where a user accidentally or inadvertently initiates an update or upgrade, for example, when prompted in control panel or using Softaculous to upgrade.

It would be really helpful therefore, and prudent, if users could cancel the upgrade process and revert to their original version of Moodle if they initiative an update and then realise they do not have the correct version of Maria DB or do not wish to continue.