If you enter an incorrect URL (http:/localhost:59991/test) [note the single / ], the API will save. Attempting to enable this API, however, will lock up every page on the broker UI:
The API doesn't actually get enabled, because its triggered the cooldown backoff, however this doesn't actually appear to revert after 30 or 60 seconds - the error will stay until service restart. Upon service restart the UI will work again, but break if you attempt to enable the same API again.
Customer support service by UserEcho