Upgrade to 9.1.6 -- Calendar won't install/enable


I'll get some more information depending on where we get to.

Today, I upgraded from 9.1.5 to 9.1.6 (this is an existing install of OC I've had for ages). When I went in to reneable the calendar app, I got an error:

Signature could not get checked. Please contact the app developer and check your admin screen.

On the admin page, I see this message:
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


  • calendar
      • OC\IntegrityCheck\Exceptions\InvalidSignatureException
      • Certificate has been revoked.

Raw output

[calendar] => Array
[EXCEPTION] => Array
[class] => OC\IntegrityCheck\Exceptions\InvalidSignatureException
[message] => Certificate has been revoked.



This looks like purely a calendar issue (not a core OC issue), correct? I found a few posts in the store about this same thing...

Like I said at the start, I can post any info you guys think might be helpful if you really think it is a core OC issue.....

Hi, I've got it from Tom42.



I just have used the search function of the forums:


and found the solution in an existing thread:

Hi christianlx, please refer to https://github.com/owncloud/calendar/issues/800 where you will find a solution for the "Certificate has been revoked" warning.

Thanks. I can't believe I never thought to search for Certificate has been revoked. That's what I get for trying to do something after a weekend of very very limited sleep. Thanks for the reply.