Janitor is an addon for Kodi that will automatically scan your library for watched movies, TV show episodes and music videos based on criteria such as age, rating or free disk space. I set it up to delete what we already saw after 2 days except if it is in a protected folder. It is a great tool to free up disk space on your device, but if you upgrade to a version of Kodi that is not supported, it will be disabled and you will have to delete stuff manually again.
Luckily you can force Janitor to work again by editing its addon.xml file which you can find at the following location:
Open up the addons.xml file and look for the following lines:
You need to replace the version information on those lines with the correct version string for your version of Kodi that you can find in the documentation here: https://kodi.wiki/view/Addon.xml#Dependency_versions
As you can see, I already updated the versions to match those of Matrix. After saving the file and restarting Kodi, Janitor worked for me again.