Mac restarts after shutting down on Catalina
Why does computer restart???
iMac 21.5", macOS 10.15
Question marked as
How often or long does it take?
Safe Boot from the HD, (holding Shift key down at startup), does the problem occur in Safe Mode?
EtreCheck is a simple little app to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac.
http://www.etresoft.com/etrecheck
Pastebin is a good place to paste the whole report...
Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck.