For a while, I have had a notification "Couldn't install system update."
Retrying the update and restarting the phone don't help.
This is the "December 2017 Security Update."
The current Android version is 7.1.2 with security patch level November 6, 2017.
How do I install the update (or make the notification go away)?
[Edit] The answer may be a factory reset (though I have not tried that yet). (I have seen this related question Xiaomi Mi A1 won't show update to Oreo, but it doesn't help me)