VS2010: "Unable to start debugging"

Question

My VS2010 debugger has stopped functioning suddenly today on my Dell M4500. I had reinstalled VS2008 SP1 last week, but the 2010 debugger ran fine since then, so I'm not sure its the culprit. I can launch a project once just fine, & afterwards I get a message that reads "Unable to start debugging," without any error # or explanation of why. Doing IISRESET doesn't help, I get the same message until I close VS with the entire solution and reload it. Here are some things I've tried:

• Verified I have the latest project files
  
• Repair option for VS2010
  
• Complete uninstall/reinstall VS2010
  
• Replaced Web.config with known good copy
  
• Added localhost to the list of trusted sites in IE
  
• Performed \aspnet_regiis -i in the 2.0 & 4.0 directories
  
• Through IIS Services Mgr -> Default Website:
  
  • verified Enable HTTP Keep-alives checked
    
  • placed check in Integrated Windows authentication
    
• Ensured Debug on "Any CPU" is selected
  
• Tried building to Platform targets "Any CPU," "x86" & "x64"
  
• Added DisableLoopbackCheck registry key entry in
  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
• Tested under both IIS & VS Development web server
  

Does anybody have any suggestions I can also try? Any help is very greatly appreciated!

Answer 1

Just a side note. I got a similar error in VS2013 trying to attach to chrome the error was:

Unable to attach the application 'chrome.exe' using XXX The 32 bit version of the visual studio remote debugging monitor (msvsmon.exe) cannot be used to debug 64 bit processes or 64-bit dumps. Please use the 64-bit version instead

I had to untick "Silverlight" in the web project Web section:

Answer 2

I received this same message, preventing my web project from running and opening in a browser. Turns out another developer had made a change in the project properties to "Use Custom Web Server" which pointed to an external URL instead of to the web server on my machine.

Try this:

Right-click your project in Solution Explorer - click Properties - click Web tab - under Servers click "Use Visual Studio Development Server". For reference the usual port value here is "Auto-assign Port". Best of luck.