Any install that is behind in updates past the last couple major ones would need to update via a clean install. You can take advantage of the backup and restore functions in My OSMC to bring your userdata into the clean install but the database would need a bit of manual work for that to happen since you would be restoring from an older version of Kodi. Basically you would need to go through the normal restore process and then access the terminal, stop Kodi, then delete the newest version of the A/V databases, then restart Kodi which would then force it to update the old database you restored to the system.
I don’t have a complicated setup. How do I just do the clean install?
At the top of the page there is a “download” link which you can follow to download an application that will make install media on an SD card or thumb drive.