I have an asp.net application and can debug the application fine when I click F5 (Start Debugging), hits breakpoints, no problem. When I have a web app open and I try to attach to the w3wp.exe process, I get a message saying “Unable to attach to the process. Mixed mode debugging is not supported on Windows 64-bit platforms.” Is there a way for me to attach to the process?
My asp.net application is .net 3.5, has a platform target specified as “Any CPU”, and the Configuration set to debug. I am developing on Win7 x64 bit system.
VS2008 doesn’t support mixed mode debugging in 64 bit (it runs in 32 bit itself).
VS2010 does support this.
Try just selecting T-SQL, Managed, x64 when attaching the remote debugger.
See a possible solution here: "Mixed mode debugging is not supported on Windows 64-bit platforms" when trying to attach to an ASP.NET process using Visual Studio 2008