I have Fedora 39 (KDE) running on Microsoft Surface Pro 3 with secure boot enabled.
Everything works fine with the custom theme in grub, before updating UEFI dbx.
After updating UEFI dbx, grub2 drops into prompt on reboot when custom theme is configured in the grub
Removing custom theme from /etc/default/grub or re-installing factory keys in the UEFI fixes problem
If no custom theme is used, installing UEFI dbx update causes grub to throw tpm.c: 150: unknown TPM error
I ran into the issue right after a fresh install as well on my SP3 a couple of weeks ago, but haven’t run into the issue again (out of the box grub menu) after resetting the UEFI keys and allowing Microsoft and third-party keys. I’m not sure if there had been any other updates to UEFI dbx since.
Also, did a clean install of the KDE spin of F40 beta and haven’t encountered either the TPM error or the invalid image error.
like I mentioned in my original post, resetting UEFI keys and re-installing factory keys (microsoft and third-party) fixes the issue - it removes the UEFI dbx update