Whether you use Windows, Mac, or Linux, sometimes an update gets “stuck”. Most of the time, this is caused by a race condition; something that needs to wait for something else to happen but that something else needs to wait for the first thing to happen.
One particular race condition that occurs while updating can be solved very easily. Just unplug all your USB devices.
If your machine appears to be stuck during or after attempting to apply an update, just unplug all your USB devices. It may immediately begin again. If not, wait a little and then force a shutdown by pressing and holding the power button. Once off, you may simply turn your machine back on again.
You may get a message saying that the update is being reverted back to a previous state. This is okay as the race condition has been satisfied. When the update gets reapplied, it will work as expected.