Verification failed: (0x1A) Security Violation Problem

Hi,

I am having a problem installing some Linux Distros (Linux Mint 21.1 & CloneZilla 2.8.0-27) on my Dell OptiPlex 7060 SFF PC (i7-8700) from either DVD or USB ISOs.

When I attempt the installation, it comes up with a blue screen with the text: Verification failed: (0x1A) Security Violation The strange thing is, I have used the same ISO images (verified SHA256) on this PC previously and it worked fine with no issues. Also Windows 10 install disk works fine too.

I believe the issue started after I installed the latest version of Kubuntu (22.04.2), which was released only last month. It seems that the installation changed something in my BIOS, which makes the PC only accept security keys on newer operating system installs.

Upon researching most of the evening, I found the following information (quoted from another site):
What happened here is that Canonical updated their UEFI Secure Boot signing key and your system's Secure Boot Advanced Targeting variable. In plain terms, they made it so that newer boot files they release are bootable, and older ones aren't. If you got the update and then try to boot an OS that is still using the older files, it won't work and you get a Security Violation error.

Here is some extra information quoted from another forum:

The release of Ubuntu 22.04.2 LTS was delayed a week to ensure it included the latest shim 15.7 which recently replaced the older and now deprecated keys. It's possible that your machine was updated by installation of 22.04.2 and you'll need to use updated ISOs if using Secure-uEFI if the other ISOs are using now deprecated keys. Only Ubuntu is on-topic here, and 22.04 media now is available with 22.04.2 media (if what I'm saying is correct; you'll get errors now with 22.04 or 22.04.1 media too) FYI: All OS companies (inc. Microsoft) deprecate keys on the same organized day

Is there any way to revert back to a default key, so that I can use my old installation disks without having the security issue? Is there somewhere in the Dell BIOS settings that can fix this problem?

I have upgraded the BIOS firmware to the latest and did a reset settings, but still have the same problem. I would also like to keep SecureBoot enabled at all times, if possible.

I appreciate any help on this.

Thanks in advance,

Darryl