Method not found: 'System.Type.op_Equality'

Question

I'm getting this error

System.MissingMethodException: Method not found: 'System.Type.op_Equality'.

When running a build. (likely because I'm on the Android simulator, and the JIT is catching it.)

I'm getting these warnings when building:

Target ResolveAssemblyReferences:
/Library/Frameworks/Mono.framework/Versions/2.10.9/lib/mono/4.0/Microsoft.Common.targets:  warning : Reference 'Mono.Android' not resolved
        For searchpath {CandidateAssemblyFiles}
        Warning: {CandidateAssemblyFiles} not supported currently
        For searchpath {HintPathFromItem}
        HintPath attribute not found
        For searchpath {TargetFrameworkDirectory}
        Considered target framework dir /Library/Frameworks/Mono.framework/Versions/2.10.9/lib/mono/4.0, assembly named 'Mono.Android' not found.
        For searchpath {PkgConfig}
        Considered Mono.Android, but could not find in any pkg-config files.
        For searchpath {GAC}
        Considered Mono.Android, but could not find in the GAC.
        For searchpath {RawFileName}

I've installed both Mono for Android and MonoTouch on my mac. Could this have over-written some settings?

I'm also getting these as warnings:

Target ResolveAssemblyReferences:
/Library/Frameworks/Mono.framework/Versions/2.10.9/lib/mono/4.0/Microsoft.Common.targets:  warning : Found a conflict between : 'System.Core, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' and 'System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. Using 'System.Core, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' reference.
/Library/Frameworks/Mono.framework/Versions/2.10.9/lib/mono/4.0/Microsoft.Common.targets:  warning : Found a conflict between : 'System, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' and 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. Using 'System, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' reference.
/Library/Frameworks/Mono.framework/Versions/2.10.9/lib/mono/4.0/Microsoft.Common.targets:  warning : Found a conflict between : 'System.Xml, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' and 'System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. Using 'System.Xml, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' reference.

I'm sure that there is just some setting under the project's compiler that I just don't know about.

Answer 1

It looks like you've somehow ended up building your Mono for Android project referencing 4.0 assemblies. In theory this should not be possible unless you edited the project file with a text editor (MonoDevelop will not allow you to modify the project so that this will happen).

I suggest you create a new Mono for Android project from a template, and compare the two project files to see if you can deduce what is wrong in yours.