When configuring Management Center (MC) SNMP Agent settings from the GUI under: System settings > SNMP Agent settings > Version 3:
while setting the password, you may see an error in the red bar on the bottom of the page after trying to commit the password by hitting the "Save" button:
MC 3.3.1.1 and later releases.
There is a 16 character password limit for SNMPv3 Agent.
Use a password that is 16 characters or less for SNMPv3 Agent.