Hi @ all!
Yesterday I upgraded from Ubuntu Mate 17.10 to 18.10.
After that I booted but the boot is very slow.
Error message
“amd kernel: [ 49.162975] PKCS#7 signature not signed with a trusted key
amd kernel: [ 49.162975] PKCS#7 signature not signed with a trusted key
amd kernel: [ 49.162975] PKCS#7 signature not signed with a trusted key”
before login screen apears
Before upgraded to 18.10 all my system and config was perfect and now this is bad.
Can someone help please?
Thanks!
Hi @mate2go
try running “dpkg” from the recovery menu (network cable connection required):
I also assume you mean 18.04 and not 18.10???. 
oh… I mean 18.04 
I use 18.04 X64 with UEFI-support.
before login at boot, boot freezes 40 seconds, after that error message:
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
after that mate boot into login.
In LogFile-Viewer:
kernel: [ 42.991900] nvidia: loading out-of-tree module taints kernel.
kernel: [ 42.991907] nvidia: module license ‘NVIDIA’ taints kernel.
kernel: [ 42.991908] Disabling lock debugging due to kernel taint
kernel: PKCS#7 signature not signed with a trusted key
With Ubuntu Mate 17.10 I had no problems with that, all worked perfectly. Fast boot.
Then I upgraded to 18.04 and this error appears with the boot process and slows
down my SSD-disk.
I am not contented with ubuntu mate 18. 04.
How can I fade out this error message with the boat process?
Hi @mate2go,
take out the Nvidia driver pack if you installed it, see the part about removing drivers here. 
I re-installed the nvidia-340 driver.
Error message on boot isn’t gone.
3x
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
why in UM 18.04?
in UM 17.04 on boot, not
Can I hide the error messages in grub?
here’s my grub config:
GRUB_CMDLINE_LINUX_DEFAULT=“quiet nosplash ipv6.disable=1 acpi=force reboot=acpi nouveau.blacklist=1 nomodeset video=efifb selinux=0
iommu=soft elevator=noop usbcore.autosuspend=0 usbhid.quirks=0x04D9:0xA0CD:0x20000000”
Some idea?
removed the nvidia-340 driver and re-installed it again over “Software+Updates // Drivers”
error message on boot:
3x
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
why in UM 18.04? In UM 17.04 I don’t had this error message on boot.
This error message on boot slows down my system. 
Is this in Virtualbox?
Secureboot can cause that message. Are you dual booting with Windows?
no, not in VirtualBox…
no, only UM 18.04… yes uefi, but why I get this error on boot on UM 18.04 and why not in UM 17.10? it slows down the boot
See my last answer here to you here. 
I have the exact same boot-time problem running Ubuntu 18.04 with Gnome. No MATE at all. I found this page by searching for the error message. My video “Card” is the video that comes as part of my Intel CPU. My bios etc is UEFI. Nothing from Nvidia in my system.
So I guess that mate2go’s problem has nothing to do with Nvidia hardware or software.
The problem started when I upgraded to 18.04 from 17.10, back in April when it was released.
Description: Ubuntu 18.04 LTS
Codename: bionic
Linux Who 4.15.0-23-generic #25-Ubuntu SMP Thu May 31 16:36:28 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
buster/sid
Processor: Intel® Core™ i7-7700 CPU @ 3.60GHz × 8
Graphics: Intel® HD Graphics 630 (Kaby Lake GT2)
Gnome: 3.28.2
…same here from 17.10 to 18.04
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
Clean install and have the same message.
Has anyone found a fix please?
no 
not yet…
it looks like it’s a Kernel bug/error. I use debian and have the same problem with kernel 4.18
…strange things I updated some Ubuntu Kernel packages via “Update-manager”
Now I have:
Couldn’t get size: 0x800000000000000e
PKCS#7 signature not signed with a trusted key
PKCS#7 signature not signed with a trusted key
My Kernel is:
4.15.0-36-generic
I would like to completely remove UEFI. I’m afraid I can’t how without destroying my system.
After upgrade to the last KERNEL via Update-Manager, the error message is gone…
With nvidia-340?
I’m also experiencing that problem on Kubuntu 18.10
Couldn’t get size: 0x800000000000000e error message is gone but
PKCS#7 signature not signed with a trusted key …not
I have nvidia-driver-396.
