BadImageFormatException - How to find which dll is failing to compile

My project won’t compile and I get this error message;

BadImageFormatException: Format of the executable (.exe) or library (.dll) is invalid.
Mono.Cecil.PE.ImageReader.ReadImage ()
Mono.Cecil.PE.ImageReader.ReadImageFrom (System.IO.Stream stream)
Mono.Cecil.ModuleDefinition.ReadModule (System.IO.Stream stream, Mono.Cecil.ReaderParameters parameters)
Mono.Cecil.ModuleDefinition.ReadModule (System.String fileName, Mono.Cecil.ReaderParameters parameters)
Mono.Cecil.ModuleDefinition.ReadModule (System.String fileName)
Mono.Cecil.AssemblyDefinition.ReadAssembly (System.String fileName)
UnityEditor.AssemblyReferenceChecker.CollectReferences (System.String path, Boolean withMethods, Single progressValue, Boolean ignoreSystemDlls)
UnityEditor.AssemblyReferenceChecker.GetScriptsHaveMouseEvents (System.String path)

How can I find out which DLL is not compiling?

For unity5.x, we must manage the dlls. click the dll and select platform and settings. (attached image)
Only DLLs in Assets/Editor/… are for Editor and the rest are for Plugin.
For my case, settings of admob plugin. I choosed “Adsupport, coretelephony, security,storekit”][1]