I finally bit the Keychain Access bullet and upgraded to 10.13.4...and Finder was corrupt: command-I, command-C, and other windows and screen artifacts wouldn't close by ANY means other than quitting Finder, and neither "Restart" nor "Shut Down" worked, and "Sleep" flashed on and immediately off, both from menu bar and control-power pop-up.
As a beta tester I am installing upgrades every few weeks and I never have any problems — but then my user and keychain passwords are the same. Specifically what upgrade process did you follow? Have you considered changing your keychain password to match your user password then after updating changing your keychain password back to whatever you want it to be? Certainly not ideal but if it works you could use it as a workaround.
