Upgrading Ubuntu server to 22.02 and PHP version to 8.1 gives `spl_autoload_register()` error

I upgraded my Ubuntu server from 18.02 to 22.02 and my PHP version to 8.3 (from 7.4). This then gave me the following error:

Whoops \ Exception \ ErrorException (E_NOTICE)
spl_autoload_register(): Argument #2 ($do_throw) has been ignored, spl_autoload_register() will always throw

You can see the full error on my site and I've also attached a screenshot.

I thought that downgrading to PHP version 8.1 might help, as would removing the shortcode plugin, but no, same error :-( Any ideas?

Additional context:

• System output log just gives me the same error: spl_autoload_register(): Argument #2 ($do_throw) has been ignored, spl_autoload_register() will always throw
• Grav admin panel works, my actual website does not
• I'm running Nginx
• Tools -> Reports does not indicate any errors
• These two questions are the most relevant to my problem, but did not help:

/forum/support/upgrading-from-php7-4-to-php8-1-t8911

/forum/general/server-error-e-notice-spl-autoload-register-t4594

Did you read the pinned topic about asking questions? Did you try to search the forum?

Hi @Karmalakas ! Yes I have (read the pinned topic and searched the forum). I will admit though that I am not keen on creating an MWE, since this would be quite some effort for me. I have updated the post to provide more context.

Are there plugins other than shortcode that could be throwing this error?

It makes ense, that old outdated plugins use PHP features, that are no longer supported on newer PHP versions. You could raise an issue on GitHub plugin repo. Might get updated if plugin author is up for it