If the load is expected and exceeds the product’s capacity, then the capacity should be increased so that the overload condition does not persist or reoccur. If the load does not exceed the pproduct’s capacity, then check the status of the servers hosting the Resource Providers to trouble-shoot the cause of the overload.
This measurement may not indicate an error if the discarded stack event was a reliable request, the Reliable Transfer Function was able to re-attempt, and the subsequent attempt got through.