I cannot get firmware updates to apply on a Dell XPS 9360 running Ubuntu 18.04. Files are copied to the boot partition and found upon reboot, but the update does not seem to be applied after the reboot has finished.

Update procedure

I recently upgraded this laptop from 16.04 to 18.04 and for the first time I received a notification that firmware updates are available. Clicking the notification opens Ubuntu Software which shows the available updates:

• Version 1.3.1.0 for XPS 13 9360 TPM 2.0
• Version 0.2.9.0 for XPS 13 9360 System Firmware

After pressing Update All in Ubuntu Software, I can confirm (in a terminal) that *.cab files have been copied to /boot/efi/EFI/ubuntu/fw/ and I get asked to reboot.

During reboot, a short messages confirms that the update files are found and the screen blinks a few times. To me this seems as if the system switches into update modes and applies the updates before completing the reboot.

Failed result

Afterwards, the system boots normally into Ubuntu but updates do not seem to have been applied:

• Ubuntu Software still lists the same updates
• fwupdmgr still lists the same updates
• sudo dmidecode -s bios-version still shows the old version 2.2.1 instead of 2.9.0
• cat /sys/class/tpm/tpm0/ppi/version shows version 1.3 instead of 1.3.1 (I don't know for sure if this is a valid way to check the firmware version of TPM; when trying to install tpm-tools, starting trousers.service failed)