When attempting to profile a web application hosted in IIS, the following message may appear in the "Application Settings" window:

Please specify a valid URL for your web application

The Start Profiling button is disabled.

Before profiling, ANTS Profiler attempts to check that the web address in the "URL" textbox has a valid structure by checking the scheme, host, and path components. If the "path" is empty, ANTS Profiler issues this warning, preventing profiling.

If the URL to be profiled is the root web application, a "forward-slash" character must be specified as the application path.

For instance, the URL http://localhost would be considered invalid. Changing this to http://localhost/ will allow profiling to continue.