No Source available

I am not sure what happened or if I did anything.. Now anytime I try and debug it says开发者_C百科 no source available on all BCL stuff For example, on a debug.print I get that message with

Locating source for 'f:\dd\ndp\fx\src\CompMod\System\Diagnostics\Debug.cs'. Checksum: MD5 {40 74 18 44 a8 15 28 2e 54 75 5e 40 d1 5f 6a 0}

The file 'f:\dd\ndp\fx\src\CompMod\System\Diagnostics\Debug.cs' does not exist.

Looking in script documents for 'f:\dd\ndp\fx\src\CompMod\System\Diagnostics\Debug.cs'...

Looking in the projects for 'f:\dd\ndp\fx\src\CompMod\System\Diagnostics\Debug.cs'. The file was not found in a project.

Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\crt\src\'...

Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\atlmfc\src\mfc\'...

Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\atlmfc\src\atl\'...

Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\atlmfc\include\'...

The debug source files settings for the active solution indicate that the debugger will not ask the user to find the file: f:\dd\ndp\fx\src\CompMod\System\Diagnostics\Debug.cs.

The debugger could not locate the source file 'f:\dd\ndp\fx\src\CompMod\System\Diagnostics\Debug.cs'.

This happens all the time now and I:

1. Don't have an F:
2. Enable .net framework source stepping is unchecked

Is there some other sneaky setting to make these messages go away?

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f:\dd\ndp\fx\src\... is the path to the source file on the machine that the .Net Framework was compiled on.

Go to Tools, Options, Debugging, Symbols, and select Only specified modules.
Also, uncheck Enable source server support in Debugging/General.

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In Visual Studio 2010, I had to go to Tools\Options\Debugging\Just-In-Time and uncheck "Managed"|

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Go to Tools, Options, Debugging, Symbols and select Only specified modules.
It worked for me.

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I have also seen this when somehow one of the projects in a solution has its build option in configuration manager unset. If you see this, go to the Build menu, Configuration Manager, then make sure the affected projects have the Build option checked.

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Also click on the BUILD>configuration manager, make sure the 'Configuration' tab is set to debug for your project and not release.