Creating managed DLL for Unity fails with error when importing into Unity

Question

I'm trying to build two managed DLLs for Unity from C# scripts with Visual Studio 2015. One DLL is the actual asset and one contains the editor integration.

So I have a VS solution with two projects:

MyProduct
MyProduct Editor

First I compile MyProduct and it builds MyProduct.DLL from it (with Debug config). MyProduct Editor then references that DLL because there are classes in it that it needs. I then build the MyProductEditor.dll

I then want to test them in Unity, so I import them but then I get the following error in Unity and it's not working:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: 'UnityEngine.UI, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'
  at Mono.Cecil.BaseAssemblyResolver.Resolve (Mono.Cecil.AssemblyNameReference name, Mono.Cecil.ReaderParameters parameters) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.BaseAssemblyResolver.Resolve (Mono.Cecil.AssemblyNameReference name) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.DefaultAssemblyResolver.Resolve (Mono.Cecil.AssemblyNameReference name) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.MetadataResolver.Resolve (Mono.Cecil.TypeReference type) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.ModuleDefinition.Resolve (Mono.Cecil.TypeReference type) [0x00000] in <filename unknown>:0 
  at Mono.Cecil.TypeReference.Resolve () [0x00000] in <filename unknown>:0 
  at AssemblyUpdater.Steps.MemberReferenceReplacer.MemberReferenceReplacementForProperty (Mono.Cecil.MethodReference method) [0x00000] in <filename unknown>:0 
  at AssemblyUpdater.Steps.MemberReferenceReplacer.MemberReferenceReplacementFor (Mono.Cecil.MethodReference methodReference) [0x00000] in <filename unknown>:0 
  at AssemblyUpdater.Steps.MemberReferenceReplacer.Visit (Mono.Cecil.MethodReference methodReference, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Visitor.Visit (Mono.Cecil.Cil.Instruction instruction, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Visitor.Visit (Mono.Cecil.Cil.MethodBody methodBody, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Visitor.Visit (Mono.Cecil.MethodDefinition methodDefinition, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Visitor.Visit (Mono.Cecil.TypeDefinition typeDefinition, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Visitor.Visit (Mono.Cecil.ModuleDefinition moduleDefinition, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Visitor.Visit (Mono.Cecil.AssemblyDefinition assemblyDefinition, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Visitor.Visit[AssemblyDefinition] (Mono.Cecil.AssemblyDefinition node, Unity.Cecil.Visitor.Context context) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Extensions.DoAccept[AssemblyDefinition] (Mono.Cecil.AssemblyDefinition definition, Unity.Cecil.Visitor.Visitor visitor) [0x00000] in <filename unknown>:0 
  at Unity.Cecil.Visitor.Extensions.Accept (Mono.Cecil.AssemblyDefinition assemblyDefinition, Unity.Cecil.Visitor.Visitor visitor) [0x00000] in <filename unknown>:0 
  at AssemblyUpdater.Steps.AssemblyUpdaterStepBase.Apply (AssemblyUpdater.Core.AssemblyUpdaterContext context) [0x00000] in <filename unknown>:0 
  at AssemblyUpdater.Core.AssemblyUpdaterPipeline.Run (AssemblyUpdater.Core.AssemblyUpdaterContext context) [0x00000] in <filename unknown>:0 
  at AssemblyUpdater.Application.Program.CheckForObsoleteAPIUsage (AssemblyUpdater.Application.CommandLineSpec config) [0x00000] in <filename unknown>:0 
  at AssemblyUpdater.Application.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0 
UnityEditor.Scripting.APIUpdaterHelper:DoesAssemblyRequireUpgrade(String)

Does anyone know why this happens? Because I have no clue what's going on or what could be wrong. I'm using Unity 5.2.2f1.

Answer 1

Take a look Here .

The fix is being back ported to 5.2. Don't know if it will make 5.2.3 though.