How to restore an earlier OS to Mac mini?
Catalina
[Re-Titled by Moderator]
iMac 27″, macOS 10.13
Question marked as
What year model Mac mini and what macOS is it currently running?
To get this information, go to your menu bar and select Apple > About This Mac
Why do you want to go back to an earlier macOS?
going back requires a good backup, plus a full erase and reinstall
Instead, I first suggest running EtreCheck Pro on your Mac mini.
to get a EtreCheck Pro, go to > https://etrecheck.com
Then post back here with your EtreCheck Pro report, so we can help you sort out any software issues.
following the steps, at > How to use the Add Text Feature When Post… - Apple Community