I'm on a clean install of Ubuntu Mate 18.04, the system itself is working with no issues, but I am running dmesg to look at errors and warnings. I like to try to get them all dealt with if possible even if they aren't causing obvious issues right now.

I have an Nvidia card running driver 390.48.

I've got most of the issues dealt with, but one that pops up four times says this:

PKCS#7 signature not signed with a trusted key

Here are +/- three lines in dmesg for context for two of the occurrences (the second one actually captures two):

[    1.157284] ata3: SATA max UDMA/133 abar m2048@0xdf34b000 port 0xdf34b200 irq 126
[    1.157285] ata4: SATA max UDMA/133 abar m2048@0xdf34b000 port 0xdf34b280 irq 126
[    1.157535] e1000e 0000:00:1f.6: Interrupt Throttling Rate (ints/sec) set to dynamic conservative mode
[    1.168128] PKCS#7 signature not signed with a trusted key
[    1.168135] nvidia: loading out-of-tree module taints kernel.
[    1.168138] nvidia: module license 'NVIDIA' taints kernel.
[    1.168138] Disabling lock debugging due to kernel taint


[    1.175479] nvidia-nvlink: Nvlink Core is being initialized, major device number 238
[    1.175681] nvidia 0000:01:00.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none:owns=io+mem
[    1.175734] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  390.48  Thu Mar 22 00:42:57 PDT 2018 (using threaded interrupts)
[    1.180047] PKCS#7 signature not signed with a trusted key
[    1.181035] nvidia-modeset: Loading NVIDIA Kernel Mode Setting Driver for UNIX platforms  390.48  Wed Mar 21 23:48:34 PDT 2018
[    1.181409] PKCS#7 signature not signed with a trusted key
[    1.181814] [drm] [nvidia-drm] [GPU ID 0x00000100] Loading driver

The line in question is the PKCS line, I understand the driver will "taint" the kernel. From the context it seems like the PKCS warnings are related to the Nvidia driver. Is that expected? This is the driver obtained from the Ubuntu repository, not independently from Nvidia, if that makes a difference. Usually I can look up the Nvidia-specific errors and warnings (which are usually harmless) but this one I didn't find anything.


3 Answers 3


I was able to fix it it seems. Just make sure you delete absolutely everything related to nvidia(purge including all configs and i386 as well). Make sure dpkg -l | grep nvidia returns an empty result. Then go for:

sudo apt install nvidia-driver-396

(version can vary, of course)

It opens up a graphical interface inside your terminal at some point and proposes to add a signing MOK key. After I did that I rebooted and entered the key when prompted.

  • 2
    Right, I think this warning has to do with the driver not being signed, which makes no difference if you're not using secure boot (which I wasn't at the time, and I didn't really realize what it was). I've recently started using secure boot, and indeed Ubuntu 18.04 took me to the MOK signing step after a reboot.
    – mock_blatt
    Oct 13, 2018 at 4:41
  • Probably the general case would be getting the correct package from sudo ubuntu-drivers list. Dec 23, 2018 at 23:07
  • 3
    I followed these steps but wasn't presented with the option to sign an MOK key
    – Jonno_FTW
    Jan 3, 2019 at 5:59
  • @Jonno_FTW, I was prompted when installing Ubuntu 18.04, when I asked it to install proprietary drivers it said it was going to restart and to select a password for the MOK signing. On restart I had to enter that password (after going through a few menus). If you're not using secure boot it may not care? I think that was the case when I originally wrote this question.
    – mock_blatt
    Apr 30, 2019 at 15:50

I likewise have an Nvidia card using the proprietary Nvidia driver.

On first boot after upgrading from 17.10 to 18.04 by the message:

PKCS#7 signature not signed with a trusted key

was reported 3 times before reaching the login screen and the boot-sequence stalled. I could only boot in Recovery Mode. Disabling Secure Boot in the BIOS made no difference.

Having booted in Recovery Mode, however, I could select Resume normal boot from the action menu and a normal boot sequence then proceeded successfully.

I launched Software & Updates and opened the Additional Drivers tab. Under 17.10, my Nvidia graphics card driver had been been the proprietary one provided by the Ubuntu nvidia-driver-390 meta-package. Now, the card was not reported as using that proprietary driver, or the open-source xorg-xserver-video-noveau driver. It was shown as using a manually installed driver, and the usual proprietary and open-source driver options were unselectable.

I then established by:

dpkg -l nvidia-driver-390

that nvidia-driver-390 was no longer installed. So I installed it:

sudo apt install nvidia-driver-390

Then rebooted, and the boot sequence ran successfully and normally. After logging in I revisited Software & Updates -> Additional Drivers and now saw that my graphics card was reported as using the proprietary nvidia-driver-390 driver.

  • 1
    You had a worse situation than me, glad you got it sorted out. Out of curiosity, if you run dmesg | grep -C 3 PKCS do you see something similar to me? For me, it's asymptomatic but I know that can change.
    – mock_blatt
    May 9, 2018 at 0:46

I was able to circumvent this issue by first purging the installed NVIDIA driver. then reboot and also make sure your secure boot is disabled. go through the installation once more. except this time when the MOK message prompted click "NO" to set a new machine owner key. worked on Ubuntu 16. NVIDIA-460

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