huseyint huseyint - 6 months ago 54
C# Question

Cannot step into .NET framework source code

I am using Visual Studio 2013 and have a .NET 4.5.2 project. I have setup my settings according to following page:

With this setup, I can see that all necessary symbols are downloaded and loaded but I cannot step into a code like the following:

var cookieContainer = new System.Net.CookieContainer();

I am getting a Source Not Available message.

I can step into the following code just fine:


Do you have any idea why I can step into code from mscorlib.dll but cannot step into code from System.dll?


and have a .NET 4.5.2 project

The version number is your problem. It is a general problem with the Reference Source, Microsoft does not keep it updated well enough to supply source for new framework versions. And more troubling, for security and stability updates. The guys that worked on this are well aware of this problem, they noted this as an issue in their presentation but it has currently, and always had, the status of a // todo item.

It is something you can visualize, first delete System.pdb from your symbol cache (the one in MicrosoftPublicSymbols). Then start debugging your test program, the debugger will retrieve a new PDB from the server. Use Debug > Windows > Modules, right-click System.dll and select "Symbol Load Information". On my machine that looks like:

C:\projects2\ConsoleApplication407\bin\Debug\System.pdb: Cannot find or open the PDB file.
C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.pdb: Cannot find or open the PDB file.
C:\Windows\System.pdb: Cannot find or open the PDB file.
C:\Windows\symbols\dll\System.pdb: Cannot find or open the PDB file.
C:\Windows\dll\System.pdb: Cannot find or open the PDB file.
C:\temp\symbols\System.pdb\c464b02c2bf04080adcad166dc729c151\System.pdb: Cannot find or open the PDB file.
C:\temp\symbols\MicrosoftPublicSymbols\System.pdb\c464b02c2bf04080adcad166dc729c151\System.pdb: Cannot find or open the PDB file.
SYMSRV:  C:\temp\symbols\System.pdb\C464B02C2BF04080ADCAD166DC729C151\System.pdb not found
SYMSRV: not found Symbols not found on symbol server.
SYMSRV:  System.pdb from 96985 bytes Symbols downloaded from symbol server.
C:\temp\symbols\System.pdb\C464B02C2BF04080ADCAD166DC729C151\System.pdb: Symbols loaded.

You can see it searching for the PDB in the normal locations and not finding it. Then contacting the SYMSRV. It first goes to, as it should, but that server says "not found". And you'll get the copy from the regular msdl server, the stripped one that doesn't have the necessary file + line number debugging info.

There is no clean fix for this, you'd have to downgrade your machine again to the reference source version. Something I cannot do, using Windows 8.1. And should not do, I use VS2013. Redgate's Reflector is an alternative.

I created a UserVoice item for this, it needs a lot more votes.

Update: the Reference Source is now updated to 4.5.2 (March 2015)