Today, I wanted to create a new Performance Session in Visual Studio to trace an detect some slowly parts in my web application application.

So it easy, I use the wizard to select my website and the different DLLs I want to instrument, I launch everything and what do I get ?

Launch Error: The web site could not be configured correctly; getting ASP.NET process information failed. Requesting 'http://localhost:48185/MyAspApp/VSEnterpriseHelper.axd' returned an error: The information returned is invalid.
PRF0017: Can't launch server for 'C:\.....\Project'.

What's happen ? I have found some information on Microsoft's website and on some blogs.

Here are two things you can check to correct the error

• Be sure your website / web app uses dynamic port
• Be sure you website / web app do not use forms authentication
  • If it's the case, correct it to add a tag allow users="?" and allow users="*" 

In my cases, it has resolved my problem.