I had this exact problem that was beyond frustrating because all the forums I searched and tried did not solve my issue. Turns out the problem was local and I finally figured out what to do so if anyone reading this is experiencing this same message, try this:
1. Go to finder window
2. At the very top where the menu is, click on 'Go'
3. Hold the 'option' key and a 'Library' should suddenly appear in the dropdown list. Click it.
4. Navigate to the folder called 'Keychain'
5. Drag and drop it to desktop
6. Restart
7. After reboot, it may or may not ask you first thing to enter your appleID password. Enter it.
8. Now go to Systems Preferences > iCloud
9. You should now see that Keychain is no longer checked, and you should be able to then trash the folder on your desktop
Be aware that doing this does mean you will lose your saved passwords and/or credit cards stored, but there aren't any other options (at least that I came across) to resolve this issue anyway. In my case, I was so frustrated with the approval messages popping up on my other devices and keychain being stuck in the pending state, that I gladly was willing to start over.