Unfortunately your screenshot does not show the agent type, so I'm a bit unclear on the problem.
However the "Subagent mismatch" problem happens when an agent (such as a WebServer agent) is not running the same version as the local Master Agent process. The WebServer is unique in that it talks thru shared memory to a local 'Master Agent' process, which itself talks upstream to the collector.
The most common solution is to simply restart the subagent and monitored process. Both should come up and resync on the agent version and all should start working. If this solution does not resolve your issue, perhaps you can give us a larger screenshot of the Agents Overview showing all your agents, and be sure we can see which agent is showing the error.