Xamarin IOS build error in visual studio 2017

Question

I try to build an old Xamarin project in Visual Studio 2017 but fail with the following error:

Severity    Code    Description Project File    Line    Suppression State
Error       Failed to resolve assembly: 'Xamarin.iOS, Version=0.0.0.0,     Culture=neutral, PublicKeyToken=84e04ff9cfb79065'
   at Mono.Cecil.BaseAssemblyResolver.Resolve(AssemblyNameReference name, ReaderParameters parameters)
   at Mono.Cecil.DefaultAssemblyResolver.Resolve(AssemblyNameReference name)
   at Mono.Cecil.MetadataResolver.Resolve(TypeReference type)
   at Mono.Cecil.TypeReference.Resolve()
   at Mono.Cecil.Mixin.CheckedResolve(TypeReference self)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeEnum(TypeReference enum_type)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeElementValue(TypeReference type)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeElement(TypeReference type)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeFixedArgument(TypeReference type)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeConstructorArguments(CustomAttribute attribute, Collection`1 parameters)
   at Mono.Cecil.MetadataReader.ReadCustomAttributeSignature(CustomAttribute attribute)
   at Mono.Cecil.CustomAttribute.<Resolve>b__2(CustomAttribute attribute, MetadataReader reader)
   at Mono.Cecil.ModuleDefinition.Read[TItem,TRet](TItem item, Func`3 read)
   at Mono.Cecil.CustomAttribute.Resolve()
   at Mono.Cecil.CustomAttribute.get_ConstructorArguments()
   at Mono.Cecil.ImmediateModuleReader.ReadCustomAttributes(ICustomAttributeProvider provider)
   at Mono.Cecil.ImmediateModuleReader.ReadMethods(TypeDefinition type)
   at Mono.Cecil.ImmediateModuleReader.ReadType(TypeDefinition type)
   at Mono.Cecil.ImmediateModuleReader.ReadTypes(Collection`1 types)
   at Mono.Cecil.ImmediateModuleReader.ReadModule(ModuleDefinition module)
   at Mono.Cecil.ModuleWriter.WriteModuleTo(ModuleDefinition module, Stream stream, WriterParameters parameters)
   at Mono.Cecil.ModuleDefinition.Write(Stream stream, WriterParameters parameters)
   at Mono.Cecil.ModuleDefinition.Write(String fileName, WriterParameters parameters)
   at Xamarin.Build.Download.XamarinBuildiOSResourceRestore.MergeResources(IAssemblyResolver resolver, String originalAsmPath, String mergedAsmPath, List`1 resourceItems)              

The reference for Xamarin.IOS looks OK in the project, and is pointing to:

C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\ReferenceAssemblies\Microsoft\Framework\Xamarin.iOS\v1.0\Xamarin.iOS.dll

And the project is working on a team members computer but not mine. So I guess it has something to do with versioning.

Some tips?

Answer 1

I had this problem and found that my old Xamarin.iOS project was referencing the Xamarin.Build.Download nuget package with version 0.4.2. Updating to version 0.4.7 (current at time of this post) and then rebuilding the entire solution solved the issue for me.