After Upgrade to Mate 18.04 boot problems - not trusted key

I have the same problem! It happens when I tried to resize my Windows partition or when I re-install windows…

[   1.123158] tpm_crb MSFT0101:00: [Firmware Bug]: ACPI region does not cover the entire command/response buffer. [mem 0xfed40000-0xfed4087f flags 0x201] vs fed40080 f80
[   1.123204] tpm_crb MSFT0101:00: [Firmware Bug]: ACPI region does not cover the entire command/response buffer. [mem 0xfed40000-0xfed4087f flags 0x201] vs fed40080 f80
[   1.206041] Couldn't get size: 0x800000000000000e
[   1.768668] PKCS#7 signature not signed with a trusted key
[   1.911549] PKCS#7 signature not signed with a trusted key
[   1.912823] PKCS#7 signature not signed with a trusted key

Welcome to emergency mode! After logging in, type "journalctl -xb" to view system logs,
"systemctl reboot" to reboot, "systemctl default" or ^D to try again to boot into dafault mode.
Press Enter for maintenance (or press control-D to continue):

I’m also on 18.04 and I use the nvidia-driver-415, though I think this is unrelated.

After some updates in UbuntuMate_v18.04, also the new kernel version “4.15.0-43-generic”

I got back this error:

Couldn’t get size: 0x800000000000000e

The Ubuntu Mate Team should fix that. :wink:

"fixed" with new Updates of Ubuntu-Mate.

Good news :slight_smile:

I have done a workaround with 'GRUB' to BOOT Ubuntu-Mate
faster with systemd-message "PKCS#7 signature not signed with a trusted key"

I use CSM mode in bios.

Here it is, for AMD-System with iommu=on.
I added to "/etc/default/grub":

GRUB_CMDLINE_LINUX_DEFAULT="quiet nosplash nopersistence noprompt timezone=Etc/UTC block.events_dfl_poll_msecs=1000 noautologin slab_nomerge slub_debug=FZP mce=0 vsyscall=none page_poison=1 pti=on kpti=on spectre_v2=on nobp=1 spec_store_bypass_disable=on video=vesafb:off,efifb:off nouveau.modeset=0 modprobe.blacklist=nouveau rd.driver.blacklist=nouveau amd_iommu=on pcie_aspm.policy=performance acpi=ht acpi_osi=Linux acpi_backlight=vendor"

I don't take any responsibility for it!

It works for me.