There is some type of error that has developed between the current version of Safari and Catalina 10.15.3. When you try to Delete or Add a New Bookmark in Safari you get this error message, “You can’t change your bookmarks right now because they are being synchronized. Wait a few minutes, and then try again.” Trying again in a few minutes does not work. I have tried all kinds of things to fix this without success until I finally came up with this information. If you are having this issue, then read on for a solution that worked for me and for others.
Safari & iCloud
If you stop to read the error message, it is all about bookmarks being synced. So, where do most of us sync bookmarks? We sync them with iCloud right? Try this fix for this problem. Quit Safari and then go into the iCloud Preferences area:
The iCloud Preferences are now in your Apple ID area. Once in this window you will be looking at all the Apps and services that are synced with iCloud and thus with your other Apple Devices:
If you look down the list, one of those Apps is Safari. Just uncheck Safari for syncing:
Then close the window and Restart your Mac. You may not need to do a Restart, but it cannot hurt to force all your connecting services to re-connect so to speak.
Once your machine is booted up again, open Safari and try to Add or Delete a bookmark. Hopefully, it will work just fine. After running Safari for a few minutes I went in and activated Safari iCloud syncing once again. This caused this error to return when I tried to Delete a bookmark. So, I just unchecked the box for Safari Syncing for now awaiting a fix from Apple.
If its any consolation, I booted into my Catalina Developer 10.15.3 Beta 3. The problem is not present there, Safari Delete and Add of bookmarks works just fine. I hope that carries over into the final release of this Beta.
I am sure Apple will work out this bug in the next Catalina and/or Safari release, at least I hope they will.