Dell BIOS update failing

[Harry_A]

I think this could be the solution to your problem, I also have a Dell laptop and had a very similar issue

"Failed to install important system update error"

This is normally related to a firmware upgrade. The firmware upgrade is OK but the error gets reported anyway. If you search for a file containing the text <UID> in /var using grep, for example: sudo grep -rnw /var/ -e '570d24e21cec6aadc4c7019ea2d7cfc16c22191b' you will more than likely find /var/lib/fwupd/pending.db. Deleted this file and restart. The message will then be gone.