Signing certificate not found: CN=COMODO RSA Certification Authority, O=COMODO CA Limited, L=Salford, S=Greater Manchester, C=GB
The reason behind this one, worries me a bit. Our sys-admin was cleaning out some old expired keys. When he did, we got this error.
The way that we resolved it was
1. Go into the database for IdentityServer
2. Find the table named KeyMaterialConfiguration
3. Set the SigningCertificatename to NULL
4. Go to the web page for your IdentityServer. It will now ask you to pick a certificate.
5. Everything works again
This solution makes my skin crawl. I don’t like the idea of allowing [the very next person who gets to this server] to choose an encryption key.
I also wonder if this could be resolved by refreshing the app pool.
If there is not a simple way of fixing this (by reboot, etc), Then I’m going to work on a coding tweak that will detect this error and change the database to simply choose another (arbitrary) key from the list and add a warning message at the bottom of the screen.