How to Debug a Referenced Dll (Having Pdb)

How to debug a referenced dll (having pdb)

If you have a project reference, it should work immediately.

If it is a file (dll) reference, you need the debugging symbols (the "pdb" file) to be in the same folder as the dll. Check that your projects are generating debug symbols (project properties => Build => Advanced => Output / Debug Info = full); and if you have copied the dll, put the pdb with it.

You can also load symbols directly in the IDE if you don't want to copy any files, but it is more work.

The easiest option is to use project references!

Visual Studio: Debugging a referenced DLL, I have source in another SLN

Rebuild the second solution in Debug mode on your own machine (so that file paths in that PDB are specific to your machine).

Copy both the .DLL and .PDB files to your references folder. Visual Studio will pick up the .PDB file automatically and use the file paths to show source.

You can also use Symbol Server and Source Server to achieve this when the referenced assembly is built elsewhere: http://msdn.microsoft.com/en-us/library/vstudio/ms241613.aspx

How to debug (step into) a class library referenced in my project and has .pdb and source code?

Most common reasons of such experience are:

1. enabled "my code only" (tools->options->debugging)
2. mismatched PDBs
3. mismatched sources

You've ruled out 1, so to check the other 2:

Open Debug->Windows->Modules and find assembly you are having problem with. Make sure it is loaded from location you expect, has version you expect, check if PDBs are loaded. You may need to try load/reload PDB to see if VS is happy with PDB it located.

If PDBs are matching VS should start asking about source location. Information about source is part of PDB so it will let you know if source matches or not (there is option to allow loading mismatched source files, but you'll get funny debugging expirience).

Note that if you library build for RELEASE it will be optimized and for some function you'll not be able to debug them at all due to inlining at JIT time or compile time optimizations of dead code (like if (false) branches). For best expirience make sure to use DEBUG assembly with matching PDB and make sure to attach early with "suppress optimizations on load" in debugger options.

How NOT to debug a referenced dll?

Since there is a very small chance that it's possible to do what I first wanted, second best solution is to automatically switch between NuGets and this works with Choose-When-Otherwise. Condition in PackageReference or in ItemGroup doesn't work (at least not in VisualStudio, according to this). So I'll create two NuGets, one will be Release with tampering detection and the other will also be Release but without tampering detection ("-debug" suffix is added to this version). NuGet is then not installed through NuGet Manager but only the dllVersion is updated in .csproj:

<PropertyGroup>
  <dllVersion>1.2.3</dllVersion>
</PropertyGroup>
<Choose>
  <When Condition="'$(Configuration)'=='Debug'">
    <ItemGroup>
      <PackageReference Include="dllNuGet" Version=$(dllVersion)-debug/>
    </ItemGroup>
  </When>
  <Otherwise>
    <ItemGroup>
      <PackageReference Include="dllNuGet" Version=$(dllVersion)/>
    </ItemGroup>
  </Otherwise>
</Choose>

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