My integrity check fails with Invalid Signature Exception in it

Opening Rant

I’m having a déjà vu from this problem but looking around at all the posts I have here and on Git, as well as other people’s posts, they all seem too different from this specific case that I think I have no way to know what to do. :slightly_frowning_face:

Nextcloud version: 17.0.3
Operating system and version: Ubuntu Linux 18.04.1
Apache version: 2.4.41
PHP version(s): 7.3.14, 7.4.2, but I’m pretty sure the Nextcloud uses the 7.3 version.

The issue you are facing:
After opening the https://sd.fqdn.tld/index.php/settings/admin/overview page the code integrity check fails:

Technical information
The following list covers which files have failed the integrity check. Please read
the previous linked documentation to learn more about the errors and how to fix

- secsignid
		- OC\IntegrityCheck\Exceptions\InvalidSignatureException
		- Signature could not get verified.

Raw output
    [secsignid] => Array
            [EXCEPTION] => Array
                    [class] => OC\IntegrityCheck\Exceptions\InvalidSignatureException
                    [message] => Signature could not get verified.

Rescan produces the same results. Looking at the suggested documentation didn’t help either.

Is this the first time you’ve seen this error? : Y (kind of)

Steps to replicate it:

  1. Unknown

Last time I got through a code integrity check cleanly was at the end of this particular Git Issue:
A new kind of failure when upgrading to 17 from 16, NULL page loads where Start Update should. #18277

Towards the end of that fiasco, I was guided through a difficulty with the check, but that problem is distinctly different from this one.

The only thing I did since then which gives a reason for suspicion (or is just a red-herring), is this little number here in Git:
Chrome : Geolocation error: Geolocation has been disabled in this document by Feature Policy… #229
However, I did perfectly reverse that alteration before this code integrity check, so I don’t think it’s the same situation either.

I vaguely remember somebody giving me a command-line way to do a resetting of the checksum things, but still, this seems like a different problem.