When testing the url_response probe with a bad url/wrong port/etc instead of showing a failure, it hangs for a long time and then causes a communication error in the probe GUI.
url_response 4.56
defect
This will be resolved in the next release of url_response - as yet unscheduled.
This only affects the Test button and not the operation of the probe, so if you need to monitor a "known bad" URL, downgrade to the previous version of url_response (4.52) for creating and testing the profile, and then you may upgrade to 4.56 again to run the profile if desired.