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

I had the same issue but it worked when I switch Build => Platform target from x64 to x86.

Answer 2

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 3

Here's why I got this error.

In Debug properties, verify that Start external program is not empty. VS 2010 will warn you about it being empty, but will let you save it

I was trying to switch it from IE to Chrome, lost track of changes I was making, and spent an hour trying to figure out where this error was coming from.

Answer 4

Kindly turned off Debug Edit and Continue option

Turn on vs2010, run debug.

turn off debug, shut down all lunched webServers (i had few of them for different services)

Turn off VS2010

Turn on VS2010.

After that everything works perfect.

Answer 5

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.