Symptoms

When going through and doing a health check on the environment the below error was found in the Event Viewer:

Subject Name: CN=K2 OAuth High Trust
Issuer Name: CN=K2 OAuth High Trust
Thumbprint: 5FA7BBB7E11F0BAC5EC63019F672ACDFDD296B57
Errors:
The root of the certificate chain is not a trusted root authority.
 

Diagnoses

This thrown error indicates that there may be issues with communication between K2 and Sharepoint since the K2 OAuth High Trust certificate verifies that connections between these two parties are trusted. These errors do not show for users and are only seen in the Event Viewer. The error itself is complaining that the top most cert is not trusted. However, this cert is self signing and also the K2 OAuth High Trust certificate is the highest in the chain of trusted root authority. In essence this certificate is complaining about itself. The certificate was verified to not be expired in the mmc snap-in for certificates and it was installed on only the K2 server as required.
 

Resolution

Running through K2 for Sharepoint Setup manager and selecting the repair option can clear up this error message and ensure that the necessary components are added. It is also recommend that AppDeployment.exe is run with the Analyze Sharepoint Configuration option selected. Health check verifies the High Trust Certificate and ensures that all sharepoint components and configurations are set properly.

In the K2 for Sharepoint installation folder there should also be some powershell scripts created by appdeployment.exe named SetupS2S-2SITECOLLECTIONNAME]-EPORT].ps1. The file name will have the specific site collection and port based on your environment. Run through this and see if it returns any errors.