Subject: If you're feeling the urge to pentest ...
Author:
Posted on: 2017-03-07 06:00:00 UTC
... or otherwise poke at the boundaries of the code running here, please use your own YourWebApps instance, since this one is in active use.
And if you do manage to replicate this (again, I'd prefer you not try here), please let me know how you hit that error page.
(It's possible you were hitting an admin interface of some sort, but that wouldn't explain the long binary blob in the URL)