Why am I getting "The server committed a protocol violation Section-ResponseStatusLine" when debugging my web application?

Question

I have a .NET 1.1 solution where all projects have been upgraded to .NET 4.0 (VS2010, Windows 7). To get past my "Unable to start debugging on the web server" problem, I switched my web application property to use VS Development Server instead of IIS.

When debugging the web application, it launches OK. But I get the above error when I hit a line where I call a web service that's local on my machine. I've seen stuff about adding useUnsafeHeaderParsing=false, but my web.config doesn't have a sytem.net section.

Is it not able to server the web service as well as the web application simultaneously on the application development server? Do I need to get it configured correctly to use IIS7? As a longtime IIS6 user, just looking at it makes my head spin... although, I do have the site and webservices set up within it, and I am fairly certain it worked at one time. Gotta love that.

Answer 1

This worked for me: Text below is comming from This CodePlex Post

This error usually occurs when you have set up Visual Studio to debug an existing web application running in IIS rather than the built in ASP.NET debug web server. IIS by default listens for web requests on port 80. In this case, another application is already listening for requests on port 80. Typically, the offending application is Skype, which by default takes over listening on ports 80 and 443 when installed. Skype is already occupy the port 80. So IIS is unable to start.

To resolve the issue follow the steps:
- Skype -> Tools -> Options -> Advanced -> Connection:
- Uncheck "Use port 80 and 443 as alternatives for incoming connections".

Answer 2

Its due to Skype has taken default Port 80 or 443 and Default website is stopped. to solve this issue, close Skype, [Start] Default Website from IIS, (and start skype again if you want.)