As a rule of thumb, if my computer is working without any problems, I'll just ignore warnings and errors that show up during boot or shutdown.

Did a search for ubuntu "integrity: problem loading x.509 certificate" and the first result indicates out of date bios certificates needed for secure boot on older laptops. Disabling secure boot seems to be the suggested fix.

As far as I know, other distributions just don't show these errors, but Ubuntu choose to show them.

Most of them are just due too a BIOS implementation that is not entirely up to standards, from what I understand. It seems some manufacturers have chosen to make their system easier to use with Windows instead of strictly enforcing standards.

I just ignore the errors. As long as everything works properly, I feel fine with that.

Kernel boot logs aren't well disciplined to be careful about what is an error or not. Sometimes it's just checking for the existence of hardware and reports the error it gets if it doesn't exist.

If things are working I wouldn't worry.

It's a thing with certain laptops, where their secure boot certs are outdated or something. Not really anything you can do to fix, but it doesnt mean anything in practice - I never had issues with it after running linux across multiple distros about a year on my Acer nitro 5.

only thing you might have issues with is using secure boot in certain distros but if you don't have problems then no need to worry

X.509 certs are commonly used in TLS/HTTPS.

Why is one needed in your boot process?

Is your drive encrypted?

Mmmm, confit errors 😋🍽️