Fody Exception in Release Mode Symbol file .dll.mdb does not match assembly .dll

Question

I'm having a problems building a PCL in Xamarin Studio on the Mac. It works fine in debug mode but fody throws an exception in Release Mode.

Exception during build is listed below.

Error: Fody: An unhandled exception occurred:
Exception:
Symbol file `XXX/obj/Release/XXX.dll.mdb' does not match assembly `XXX/obj/Release/XXX.dll'
StackTrace:
at Mono.CompilerServices.SymbolWriter.MonoSymbolFile.CheckGuidMatch (Guid other, System.String filename, System.String assembly) [0x00000] in <filename unknown>:0 
  at Mono.CompilerServices.SymbolWriter.MonoSymbolFile..ctor (System.String filename, Mono.Cecil.ModuleDefinition module) [0x00000] in <filename unknown>:0 
  at Mono.CompilerServices.SymbolWriter.MonoSymbolFile.ReadSymbolFile (Mono.Cecil.ModuleDefinition module, System.String filename) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.Mdb.MdbReaderProvider.GetSymbolReader (Mono.Cecil.ModuleDefinition module, System.String fileName) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.ModuleReader.ReadSymbols (Mono.Cecil.ModuleDefinition module, Mono.Cecil.ReaderParameters parameters) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.ModuleReader.CreateModuleFrom (Mono.Cecil.PE.Image image, Mono.Cecil.ReaderParameters parameters) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.ModuleDefinition.ReadModule (System.IO.Stream stream, Mono.Cecil.ReaderParameters parameters) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.ModuleDefinition.ReadModule (System.String fileName, Mono.Cecil.ReaderParameters parameters) [0x00000] in <filename unknown>:0 
  at InnerWeaver.ReadModule () [0x00000] in <filename unknown>:0 
  at InnerWeaver.Execute () [0x00000] in <filename unknown>:0 
Source:
Mono.Cecil.Mdb
TargetSite:
Void CheckGuidMatch(System.Guid, System.String, System.String)

Please mark @matthewrdev has the correct solution for this issue. — jzeferino, Jun 27 '16 at 10:18

matthewrdev · Answer 1 · 2017-03-08T22:47:38.147

Fody needs the debug information (*.mdb file) associated with the outputted assembly to perform the weaving step. Release builds by default turn off the Debug Information field within Build -> Compiler in a projects settings.

Having this build option set to None disables debug symbolication and results in the mdb file getting out of sync, hence the Symbol file 'XXX/obj/Release/XXX.dll.mdb' does not match assembly XXX/obj/Release/XXX.dll exception.

Therefore you need to enable Symbols Only or Full when you build projects in release mode when Fody is integrated into the build process:

score 1 · Answer 2 · answered Oct 24 '14 at 06:12

You may have already, but I'd start with this if it was me:

Right click on your solution
Properties
Configuration Properties / Configuration

In the "Configuration" drop down in the top left, check that the "Debug" configuration (re: Platform | Build | Deploy) matches "Release".

Fody Exception in Release Mode Symbol file .dll.mdb does not match assembly .dll

2 Answers2