ASP.NET Debug in VS2008 and JavaScript Debug in IE8 at Same Time

Hi all,

I am building a website with extensive usage of jQuery to interactive with server side code to achieve Ajax. I lauch my project from VS2008 SP1 in debug mode, and my web app is displayed in IE8. Inside IE8 I hit F12 to launch developer tool, in the developer tool I click on “Script” tab, but when I click “Star Debugging” button I get error message “Unable to attach to the process. Another debugger might be attached to the process.

I launch IE8 to load any other website, repeat the steps to enable JavaScript debug and it works for me. It seems that VS2008 holds the IE process.

In VS2008->Tools->Options->Debugging->Just-In-Time I clear the check box of Script, but I still have the same error when I try to start client debug.

Anybody has clue, how can I enable JavaScript debug from IE8 developer tool when I launch the website from VS2008 debug mode?


Hello Hardy,Thanks for your post.This is expected behavior for web project  in VS 2008. When you press F5 in VS, VS will first start  a local web server  and then start an IE and attach script  debugger on it. The Just In Time debug  setting is not for this purpose. It is not configurable to stop script debugging  IE. Here are some workarounds to this problem:1. Don’t open any page in web  project’s start optionRight click  on the web project and select Properties / Web tab  / Start Actions / Select “Don’t open a page” When pressing F5, VS won’t start IE process  and you have to open IE and navigate to your web page manually.2. Detach IE process after debuggingPress F5 to start IE.In VS, open menu Debug / Windows / ProcessesYou will see iexplore.exe process in the process list. Right click on it and select DetachHope it helps.Hongye Sun [MSFT]MSDN Subscriber Support in ForumIf you have any feedback on our support, please contact msdnmg @

Hi Hardy,I am writing to follow up this issue. Please let me know if you need any further help on this. Have a nice day. 

ThanksI understand your approach 1, actually I also pressed F5 to launch  IE and then copy and paste same URL to FireFox to use other tool  to debug  JavaScript.For 2nd approach under my Debug/Windows menu, there is no “Procesess”.Hardy