Symptoms

I have several K2 workflows that are triggered when a document is added to a SharePoint library. After restarting the machine that hosts the K2 server, my workflows are no longer triggering. It's as if nothing on the SharePoint side of things has the necessary process rights anymore. I can still start workflows manually through K2 Workspace.
 

Diagnoses

We were able to narrow the issue down to the MSMQ issue. It appears that the K2 Service Account lost permission to the MessageQueue. We saw 67 items in the EventBus public queue. Every time, we tried to start on instance of the process from SharePoint, we would also see an entry get added in the queue, and in the eK2].]Eventbus].]ClientRecorderError] table.
 

Resolution

Customer’s sysadmin was able to restore the service account's permissions to the message queue, and that resolved the issue.