How to: Troubleshoot error “Attaching the Script debugger to process iexplore.exe failed. A debugger is already attached.”.

If you’re working on a Windows 7 machine, with Visual Studio 2010 and Internet Explorer 10, you will be getting an error when you attempt to debug a web project.

In order to be able to attach the debugger to Internet Explorer again, you will have to manually register the Active Debugging Proxy/Stub.

(original answer can be found here. However, you’ll have to dig a big as the answer that has been selected as appropriate, really isn’t. In any case, you should be fine as long as you just follow the steps below)


Run the command prompt with elevated privileges and run the following:

regsvr32.exe “%ProgramFiles(x86)%\Common Files\Microsoft Shared\VS7Debug\msdbg2.dll”

Be sure to have VS and IE closed at the time. Next time you try to debug, everything should work fine. If not, make sure that in the IE options, the JavaScript debugger is not disabled. To do that, view the Advanced Options and uncheck the option:

Disable script debugging (Internet Explorer)

MGR: the Intelogist

About MGR: the Intelogist

SharePoint Server developer, turned Sitefinity developer, turned Angular developer, turned SharePoint Online consultant, turned Unily consultant, turned O365 consultant... Never a dull moment!

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