The AD Op Master Response monitor failed consecutive attempts to bind or ping the schema operations master (also known as the schema flexible single master operations (FSMO) role holder)
This is more than a transient error, and it should be investigated. However, because the schema master does not have a high-availability requirement, short-term outages are not necessarily a priority, and they can be deferred..
To view all the events that are generated by the AD Op Master Response monitor, open the AD MP Events view. These events provide more detailed information about the errors that occur during testing of the operations masters.