Follow these steps to stop your Windows 10 PC from restarting when you print (March 2021).
1. Click the Start button (bottom left corner)
2. Click Settings (looks like a gear)
3. Select Update & Security
4. Click Check for Updates
5. If "Feature Update" is showing, click Download and Install. This could take a while.
6. When it completes, click the Restart Now button.
YOU'RE NOT FINISHED! Keep going! :)
6. When your computer comes back up,
go back to Settings > Update & Security and click CHECK FOR UPDATES again. This check may take several minutes!
Now an "Optional quality update available" should show up (KB5001649).
7. Click Download and install.
8. WAIT for it to install... it takes at least 15-20 minutes 
9. Click "Restart Now" when it's done.
10. ONLY NOW (AFTER this update and another RESTART) try printing something.
** If you still get a blue screen/restart, go back to Settings > Update & Security and click CHECK FOR UPDATES again. Sometimes the KB5001649 update will fail, and needs to run again.