asp.net - VS2010 error: Unable to start debugging on the web server

Question

I get error message "Unable to start debugging on the web server" in Visual Studio 2010. I clicked the Help button and followed the related suggestions without success.

This happens with a newly created local ASP.Net project when modified to use IIS instead of Cassini (which works for debugging). It prompts to set debug="true" in the web.config and then immediately pops up the error. Nothing shows up in the Event Viewer.

I am able to attach to w3wp to debug. It works but is not as convenient as F5.

I also have a similar problem with VS2008 on the same PC. Debugging used to work for both.

I have re-registered Framework 4 (aspnet_regiis -i). I ran the VS2010 repair (this is the RTM version). I am running on a Windows Server 2008 R2 x64 box.

I do have Resharper V5 installed.

There must be some configuration setting or registry value that survives the repair causing the problem.

I'd appreciate any ideas.

Answer 1

Disable the loopback check

(original microsoft page here)

To set the DisableLoopbackCheck registry key, follow these steps:

Click Start, click Run, type regedit, and then click OK.

In Registry Editor, locate and then click the following registry key: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlLsa

Right-click Lsa, point to New, and then click DWORD Value.

Type DisableLoopbackCheck, and then press ENTER.

Right-click DisableLoopbackCheck, and then click Modify.

In the Value data box, type 1, and then click OK.

Quit Registry Editor, and then restart your computer.