PDB doesn't match .exe

Question

I am using VS2015 debugger on my C++ app. When I start the app, debugger gives the message

Loaded 'C:\MyDir\Working\x64\Debug\MyApp.exe'. Cannot find or open the PDB file

As a consequence, I cannot set breakpoints.

There is a .pdb file in the same directory as the .exe, but it doesn't match, according to VS debugger, and also according to WidDBG Symchk. Symchk does not provide the reason for the mismatch, even with /v option.

Complete rebuild does not make this problem go away. It is only occurring for debug build, and it just started today. Before today, there was no problem with mismatched pdb's, either for debug or release builds.

The VS options I am using are:

C++: Debug Information Format=Program Database (/Zi), Program Database File Name=$(IntDir)%(Filename).pdb;
Linker: Generate Debug Info=Optimize for debugging (/DEBUG), Generate Program Database File=$(OutDir)MyApp.pdb, Generate Full Program Database File=Yes.

The pdb files for the individual objects appear in the intermediate directory, and MyApp.pdb appears in the output directory, along with MyApp.exe.

Now, here's the weird part: when delete the existing MyApp.pdb and then relink, a new .pdb file appears in the output directory with a current mod time. While the linker is running, the pdb file grows to be large (~70 MB), but as the linker completes, the pdb file suddenly becomes small (~4 MB), and the mod time changes to a few hours earlier today. This is very suspicious, and probably accounts for the pdb mismatch.

The linker's final output lines are

 Finished searching libraries
  MyApp.vcxproj -> C:\MyDir\Working\x64\Debug\MyApp.exe
  MyApp.vcxproj -> C:\MyDir\Working\x64\Debug\\MyApp.pdb (Full PDB)

How can I force VS to produce a matched and correct pdb file for the debug build?

Woody20 Woody20 · Accepted Answer · 2017-06-20T20:02:54

UPDATE: The problem was that there is a pdb file MyApp.pdb created in the intermediate directory (it is the pdb file created by the compiler for MyApp.cpp). For some reason, the linker replaces the "real" pdb file with this one at the end. Since they have the same name, MyApp.pdb, Symchk doesn't show a name mismatch (although there may be a timestamp mismatch that isn't evident).

It is not obvious how the debugging info for MyApp.cpp can be included in the final MyApp.pdb.

PDB doesn't match .exe

1 Answers