"ResolveAssemblyReference" task fails and System.BadImageFormatException, but assembly isn't used anywhere!

Question

I am getting an error about the assembly "C:\Ora10g\bin\Zip.exe". The trouble is this solution does NOT use anything in Oracle at all. I could not find a single reference to 10g anywhere in the project. I inherited this from another person who left our group. He never had this issue. Another member of my team said he got this before but reinstalling the client portion of 10g fixed it. No such luck there. I even tried using WinGrep to search the entire solution folder for "Ora10g" but it wasn't there.

Any ideas? I can't build this solution until I can figure out how to get rid of this false reference to Oracle.

VS 2005 solution. Contains a couple WinForm apps, a couple class libraries, and a web service. The error occurs in the main class library project.

Here is the error message:

Error   1   The "ResolveAssemblyReference" task failed unexpectedly.
System.BadImageFormatException: Could not load file or assembly 'C:\Ora10g\bin\Zip.exe' or one of its dependencies. The module was expected to contain an assembly manifest.
File name: 'C:\Ora10g\bin\Zip.exe'
   at System.Reflection.AssemblyName.nGetFileInformation(String s)
   at System.Reflection.AssemblyName.GetAssemblyName(String assemblyFile)
   at Microsoft.Build.Shared.AssemblyNameExtension.GetAssemblyNameEx(String path)
   at Microsoft.Build.Tasks.SystemState.GetAssemblyName(String path)
   at Microsoft.Build.Tasks.Resolver.FileMatchesAssemblyName(AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, Boolean allowMismatchBetweenFusionNameAndFileName, String pathToCandidateAssembly, ResolutionSearchLocation searchLocation)
   at Microsoft.Build.Tasks.Resolver.ResolveAsFile(String fullPath, AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, Boolean allowMismatchBetweenFusionNameAndFileName, ArrayList assembliesConsideredAndRejected)
   at Microsoft.Build.Tasks.Resolver.ResolveFromDirectory(AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String directory, ArrayList assembliesConsideredAndRejected)
   at Microsoft.Build.Tasks.AssemblyFoldersResolver.Resolve(AssemblyNameExtension assemblyName, String rawFileNameCandidate, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String hintPath, String assemblyFolderKey, ArrayList assembliesConsideredAndRejected, String& foundPath, Boolean& userRequestedSpecificFile)
   at Microsoft.Build.Tasks.AssemblyResolution.ResolveReference(IEnumerable`1 jaggedResolvers, AssemblyNameExtension assemblyName, String rawFileNameCandidate, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String hintPath, String assemblyFolderKey, ArrayList assembliesConsideredAndRejected, String& resolvedSearchPath, Boolean& userRequestedSpecificFile)
   at Microsoft.Build.Tasks.ReferenceTable.ResolveReference(AssemblyNameExtension assemblyName, String rawFileNameCandidate, Reference reference)
   at Microsoft.Build.Tasks.ReferenceTable.ResolveAssemblyFilenames()
   at Microsoft.Build.Tasks.ReferenceTable.ComputeClosure()
   at Microsoft.Build.Tasks.ReferenceTable.ComputeClosure(DependentAssembly[] remappedAssembliesValue, ITaskItem[] referenceAssemblyFiles, ITaskItem[] referenceAssemblyNames, ArrayList exceptions)
   at Microsoft.Build.Tasks.ResolveAssemblyReference.Execute(FileExists fileExists, DirectoryExists directoryExists, GetDirectories getDirectories, GetAssemblyName getAssemblyName, GetAssemblyMetadata getAssemblyMetadata, GetRegistrySubKeyNames getRegistrySubKeyNames, GetRegistrySubKeyDefaultValue getRegistrySubKeyDefaultValue, GetLastWriteTime getLastWriteTime)
   at Microsoft.Build.Tasks.ResolveAssemblyReference.Execute()
   at Microsoft.Build.BuildEngine.TaskEngine.ExecuteTask(ExecutionMode howToExecuteTask, Hashtable projectItemsAvailableToTask, BuildPropertyGroup projectPropertiesAvailableToTask, Boolean& taskClassWasFound)

WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

Answer 1

The give-away's are "The module was expected to contain an assembly manifest" and the fact that the exception is of type System.BadImageFormatException. Something is trying to load the file "C:\Ora10g\bin\Zip.exe" as if it was a .net assembly and it either:

• Isn't a .net assembly
• Is a .net assembly but for a version of the CLR that is later than the one you're targeting
• Is a .net assembly, but for the wrong "bitness" (unlikely given the "assembly manifest" part of the exception message).
• Is corrupted

Have you:

1. Examined your Solution file (.sln) in a text editor to look for references to this file?
2. (More likely) Examined the .csproj file for the class library to see if it contains any references to this program? It could be that there's a custom MSBuild task that's trying to load that EXE, possibly to produce ZIPped output from the build process.
3. Verified that none of the assemblies that you load themselves reference, either directly or indirectly, the Zip.exe file?
4. As Dave Van den Eynde said, have you checked that the system .targets files (the files that tell MSBuild how to do what it does) are unchanged? You can find these files in %windir%\Microsoft.NET\Framework\v2.0.50727

Other things you can try:

1. Follow the instructions in the error message and turn Assembly binding logging on, then review the log to see what Zip.exe was loaded as a dependency of.
2. "Grep" your whole harddrive for "zip.exe", something, somewhere is referencing it and it may not be in your project/solution (see point 4), but it may be somewhere else that the installer for the Oracle Client has damaged/altered.