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A couple of weeks ago I installed Ubuntu 16.04 on a HP Z420 workstation. The BIOS is labelled J61 v01.02. Yesterday Ubuntu stopped starting properly, displaying this error message:

a TPM error (7) occurred attempting to read a pcr value

After that I can either fall back to a root shell or reboot. I made some research on TPM, which is a security feature available in Intel processors. I therefore tweaked the system security settings available in the BIOS, as the image below shows:

enter image description here

I enabled in succession "Embedded Security Device" and "Reset of Embedded Security Device through OS". Still, after these changes Ubuntu is unable to start.

I just tried booting with a USB drive and it all went fine. I also took the time to check all the hard drives and no errors were reported. Therefore at this stage I doubt this is related to BIOS settings. What could be the cause? Is there something to be done about it?


Update: Badly needing this system, I took a more radical approach: reset the BIOS to factory and reinstalled Ubuntu. The latter did it somehow, Ubuntu is now able to start up correctly, even though briefly displaying the TPM error message on occasion.

Note that I will no longer be able to test suggestions related to the OS itself. If you have other remarks please leave a comment.

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  • Perhaps you can disable TPM? I think Ubuntu can't use it anyway.
    – user692175
    Nov 15, 2017 at 19:55
  • @MichaelBay How can I disable TPM in this BIOS? Nov 16, 2017 at 7:37
  • I think it is the exact same thing you enabled: Embedded Security Device
    – user692175
    Nov 16, 2017 at 7:43
  • @MichaelBay Ubuntu was unable to start either with that option enabled or disabled. Presently it is disabled, and even though the re-installed Ubuntu manages to start up it still briefly displays the TPM error. Nov 16, 2017 at 7:45

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