"No Source Available" - Visual Studio Debugging (even when symbols have loaded)

Question

I have set up Visual Studio 2012 Professional to download debug symbols. It is set up correctly and the symbols have downloaded.

I get to the line of code I wish to step into:

bool result = Membership.ValidateUser("user", "password");

I right click on it and choose step into specific-->Membership.ValidateUser()

Then a tab opens in Visual Studio saying:

No Source Available - There is no source code available for the current location

Membership.ValidateUser() is in the System.Web.Security namespace which is in the System.Web.dll. If I open up the Modules window I can clearly see that the symbols for this assembly have been downloaded.

If the symbols are there, why am I not able to step into the source code?

Answer 1

Source stepping is only available for RTM or SP releases. See PDB files for .NET Framework 3.5 SP1 not available! (i.e. System.Web.pdb 2.0.50727.4016).