I have a M-3050 out of the box that was at 18.104.22.168 and upgraded it to 22.214.171.124. I am using an 126.96.36.199 Manager. Trust was successfully created between the two but the system health status is 'bad'. System faults within the manager displays a critical error 'An internal application communication error occurred on the device during SNMP configuration request or other sensor internal communication.'. Documentation that I've found somewhat refers to an SNMP error but gives no direction on how to fix it. Any assistance is appreciated.
The system health being bad is abnormal. Generally a process or component didn't come up if that's the case. the "debug" shell command "show sensor health" can give a little more detail.
A cold boot will help determine if this is a hardware component, but I recommend opening a support ticket for further assistance.
In addition, the manager uses SNMP for control channel communiction on port 8500 UDP from the manager to the sensor. Ensure you have connectivity on that port through an other network devices (i.e. firewalls).
A wireshark capture can confirm you are getting replies.
Packet fragmentation on the port 8500 UDP port is another common problem.