Mono.Cecil throws SymbolsNotMatchingException, how to find out Method line number?

Question

I tried to use a PDB file to map the Instructions to the Sequencepoints in Mono.Cecil and find out the line number of a method. But none of the answers in any forum seems to work, because no matter what I try the SymbolsNotMatchingException is thrown with the error message

Symbols were found but are not matching the assembly".

By the way, my target "application" is a Unity Game.

Here is some code I use (side note: ProjectPath is the path to my target *.dll):

var resolver = new DefaultAssemblyResolver();
resolver.AddSearchDirectory(GetDLLsFolderToResolve(ProjectPath));

using var assembly = AssemblyDefinition.ReadAssembly(ProjectPath,
                new ReaderParameters { ReadWrite = true, AssemblyResolver = resolver, 
                    SymbolReaderProvider = new PdbReaderProvider(), ReadSymbols = true });

I have already the Mono.Cecil.dll and Mono.Cecil.Pdb.dll in the same folder due to import Mono.Cecil via NuGet. Also, the target DLL and the PDB also are in the same folder.

Does anybody have a working example? Or any idea how this error could be solved? Would be happy for any help.

Answer 1

So all the steps above are correct the way they were described. The only thing I have done wrong was, that my target DLL was modified by Mono.Cecil before (I already had read and wrote my target DLL and modified it by this way). So the DLL and the PDB was not the same anymore.

So if you want to run Mono.Cecil just once and you get the exception above do the following things:

1. Build your target application again (which should have all the DLL's and the corresponding PDB's for each DLL)
2. Add ReadSymbols = true to the ReadParameters (in my case I don't want to write, so I need only the ReadParameters)
3. Run your Mono.Cecil application

Note: This is only a solution if you want to run Mono.Cecil once. If you want to run it again over your target DLL, you have to make all steps above again.

Hopefully this will help someone!

~Sulan