Q. Google Drive cannot continue syncing because your Google Drive folder is missing. How serious is that error message?
A. Very serious. I got that message. Ignored it. Went out of town and could not access any of my Google Drive folders from the previous four months.
To fix it, click on the Google Drive icon in the upper right-hand corner of your Mac. You will get an error message: Error — Google Drive folder missing. Click on it. Click on Locate Folder. Click on Google Drive. Click Open.
If Google Drive takes a long time to open, it could be because there are so many files to compare. Click on that little Google Drive icon again. If it says comparing, that is why you have to wait so long.
Check with another device such as your smartphone. If all of your files show up, your problem should be solved.
If it was not solved, make a web search for Google technical support.