If you are seeing this error after a recent up.time upgrade, the error is likely caused by one of the following issues:

• The monitor isn't compatible with the current up.time version.  In this case, ensure that you have the latest version of the monitor (send the full monitor name to uptime Support to verify).
• One or more source files (typically .jar files) required by the monitor were lost during the upgrade.  To check this condition, search your <uptime_dir>/core folder for the .jar file(s) associated with the monitor.