Confirm if your MID Server is in a failed state due to event processing
Whether it is a MID Server that is being deployed for the first time or one that has been active for a while, there may be an occasion when the MID Server record on the instance reports that the MID Server is Down. This article describes how to confirm that your MID Server is actually down by checking event processing.
1) Check that your MID Servers are showing as down in the instance.
2) Review the diagnostics page to determine if the event queue is stuck.
3) If it is similar to the below screenshot with numerous events pending, then it is probably the event processing that is holding up the heartbeat probes from processing.
4) Go to the Scheduled Jobs table.
5) Check the events process job and check the State. If it is in an error state, change it back to ready. This should allow the event process job to continue working.
6) Check the ECC queue.
7) Check to see if the HeartbeatProbes are getting processed or not for your respective MID Server.
For more information, please review MID Server Down: A Guide on How to Restore a MID Server and MID Server Heartbeat.