Operations Manager failed to convert data in a rule or monitor into event data.
This is usually due to a misconfigured rule or monitor that Operations Manager tries to run. The rule or monitor tries to convert some data (for example from a script) into event data.
More details of what caused this issue can be found by examining the associated event in the alert context and noting the rule or monitor that caused the error (the workflow name). Then reconfigure that rule or monitor.
The following link will display all events indicating a possible problem with converting data into event data: