Build failure iOS (switched from Android to iOS)

Hi smart people,

I cannot seem to find a solution to this problem. When building for iOS, the build in Unity fails.
Some maybe good to knows:
I’ve integrated Admob package, remove the Project/Library/Il2cppBuildCache folder, tried by using a different build folder, and even took the drastic measure of rebooting Unity.
Building went fine before, but I’ve switch to Android, which built all fine aswell, and went back again to iOS and now it fails building.

Hopefully you could help me!

Thanks
Joris

UnityEditor.BuildPlayerWindow+BuildMethodException: 2 errors
  at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (UnityEditor.BuildPlayerOptions options) [0x002ce] in /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPlayerWindowBuildMethods.cs:193
  at UnityEditor.BuildPlayerWindow.CallBuildMethods (System.Boolean askForBuildLocation, UnityEditor.BuildOptions defaultBuildOptions) [0x00080] in /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPlayerWindowBuildMethods.cs:94
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:189)

0p5v.traceevents"
ExitCode: 255
Stdout:
Error: IL2CPP error (no further information about what managed code was being converted is available)
System.AggregateException: One or more errors occurred. (Unresolved type reference : System.Void in module GoogleMobileAds.dll with scope GoogleMobileAds.Common, Version=7.4.0.0, Culture=neutral, PublicKeyToken=null)
—> System.ArgumentException: Unresolved type reference : System.Void in module GoogleMobileAds.dll with scope GoogleMobileAds.Common, Version=7.4.0.0, Culture=neutral, PublicKeyToken=null
at Unity.IL2CPP.DataModel.TypeContext.GetDef(TypeReference reference) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.DataModel/TypeContext.cs:line 204
at Unity.IL2CPP.DataModel.BuildLogic.TypeReferenceResolver.ResolveTypeReference(TypeReference typeReference, MappingContext mappingContext, CecilSourcedAssemblyData assembly) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.DataModel/BuildLogic/TypeReferenceResolver.cs:line 105
at Unity.IL2CPP.DataModel.BuildLogic.TypeReferenceResolver.ResolveAssemblyTypeReferences(CecilSourcedAssemblyData assembly, ReadOnlyHashSet1 typeReferences, ReadOnlyHashSet1 genericInstances) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.DataModel/BuildLogic/TypeReferenceResolver.cs:line 47
at Unity.IL2CPP.DataModel.BuildLogic.DataModelBuilder.<>c__DisplayClass15_0.b__0(CecilSourcedAssemblyData data) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.DataModel/BuildLogic/DataModelBuilder.cs:line 193
at System.Threading.Tasks.Parallel.<>c__DisplayClass33_02.<ForEachWorker>b__0(Int32 i) at System.Threading.Tasks.Parallel.<>c__DisplayClass19_01.b__1(RangeWorker& currentWorker, Int32 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
— End of stack trace from previous location —
at System.Threading.Tasks.Parallel.<>c__DisplayClass19_01.<ForWorker>b__1(RangeWorker& currentWorker, Int32 timeout, Boolean& replicationDelegateYieldedBeforeCompletion) at System.Threading.Tasks.TaskReplicator.Replica1.ExecuteAction(Boolean& yieldedBeforeCompletion)
at System.Threading.Tasks.TaskReplicator.Replica.Execute()
— End of inner exception stack trace —
at System.Threading.Tasks.TaskReplicator.Run[TState](ReplicatableUserAction1 action, ParallelOptions options, Boolean stopOnFirstFailure) at System.Threading.Tasks.Parallel.ForWorker[TLocal](Int32 fromInclusive, Int32 toExclusive, ParallelOptions parallelOptions, Action1 body, Action2 bodyWithState, Func4 bodyWithLocal, Func1 localInit, Action1 localFinally)
— End of stack trace from previous location —
at System.Threading.Tasks.Parallel.ThrowSingleCancellationExceptionOrOtherException(ICollection exceptions, CancellationToken cancelToken, Exception otherException)
at System.Threading.Tasks.Parallel.ForWorker[TLocal](Int32 fromInclusive, Int32 toExclusive, ParallelOptions parallelOptions, Action1 body, Action2 bodyWithState, Func4 bodyWithLocal, Func1 localInit, Action1 localFinally) at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IList1 list, ParallelOptions parallelOptions, Action1 body, Action2 bodyWithState, Action3 bodyWithStateAndIndex, Func4 bodyWithStateAndLocal, Func5 bodyWithEverything, Func1 localInit, Action1 localFinally) at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable1 source, ParallelOptions parallelOptions, Action1 body, Action2 bodyWithState, Action3 bodyWithStateAndIndex, Func4 bodyWithStateAndLocal, Func5 bodyWithEverything, Func1 localInit, Action1 localFinally) at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable1 source, Action1 body) at Unity.IL2CPP.DataModel.BuildLogic.Utils.ParallelHelpers.ForEach[TSource](IEnumerable1 source, Action`1 func, Boolean enableSerial) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.DataModel/BuildLogic.Utils/ParallelHelpers.cs:line 45
at Unity.IL2CPP.DataModel.BuildLogic.DataModelBuilder.Build() in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.DataModel/BuildLogic/DataModelBuilder.cs:line 68
at Unity.IL2CPP.Contexts.Components.DataModelComponent.Load(LoadSettings loadSettings, Boolean ownsTypeContext, Boolean ownsBuilder, DataModelBuilder& builder) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP/Contexts.Components/DataModelComponent.cs:line 32
at Unity.IL2CPP.AssemblyConversion.Phases.InitializePhase.Run(AssemblyConversionContext context) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP/AssemblyConversion/Phases/InitializePhase.cs:line 19
at Unity.IL2CPP.AssemblyConversion.Classic.ClassicConverter.Run(AssemblyConversionContext context) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP/AssemblyConversion.Classic/ClassicConverter.cs:line 11
at Unity.IL2CPP.AssemblyConversion.AssemblyConverter.ConvertAssemblies(AssemblyConversionInputData data, AssemblyConversionParameters parameters, AssemblyConversionInputDataForTopLevelAccess dataForTopLevel) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP/AssemblyConversion/AssemblyConverter.cs:line 30

at il2cpp.Program.DoRun(String[ ] args, RuntimePlatform platform, Il2CppCommandLineArguments il2CppCommandLineArguments, BuildingOptions buildingOptions, Boolean throwExceptions) in /Users/bokken/build/output/unity/il2cpp/il2cpp/Program.cs:line 339
UnityEditorInternal.Runner.RunProgram (UnityEditor.Utils.Program p, System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser) (at /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPipeline/BuildUtils.cs:129)
UnityEditorInternal.Runner.RunNetCoreProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, System.Action1[T] setupStartInfo) (at /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPipeline/BuildUtils.cs:91) UnityEditorInternal.IL2CPPBuilder.RunIl2CppWithArguments (System.Collections.Generic.List1[T] arguments, System.Action1[T] setupStartInfo) (at /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:817) UnityEditorInternal.IL2CPPBuilder.ConvertPlayerDlltoCpp (UnityEditor.Il2Cpp.Il2CppBuildPipelineData data) (at /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:801) UnityEditorInternal.IL2CPPBuilder.Run () (at /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:639) UnityEditorInternal.IL2CPPUtils.RunIl2Cpp (System.String tempFolder, System.String stagingAreaData, UnityEditorInternal.IIl2CppPlatformProvider platformProvider, System.Action1[T] modifyOutputBeforeCompile, UnityEditor.RuntimeClassRegistry runtimeClassRegistry) (at /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:279)
UnityEditor.iOS.PostProcessiPhonePlayer.CrossCompileManagedDlls (UnityEditor.iOS.PostProcessiPhonePlayer+BuildSettings bs, UnityEditor.iOS.PostProcessiPhonePlayer+ProjectPaths paths, UnityEditor.AssemblyReferenceChecker checker, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport buildReport) (at /Users/bokken/build/output/unity/unity/PlatformDependent/iPhonePlayer/Extensions/Common/BuildPostProcessor.cs:932)
UnityEditor.iOS.PostProcessiPhonePlayer.PostProcess (UnityEditor.iOS.PostProcessiPhonePlayer+BuildSettings bs, UnityEditor.iOS.PostProcessiPhonePlayer+ProjectPaths paths, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport buildReport) (at /Users/bokken/build/output/unity/unity/PlatformDependent/iPhonePlayer/Extensions/Common/BuildPostProcessor.cs:755)
UnityEditor.iOS.PostProcessiPhonePlayer.PostProcess (UnityEditor.iOS.PostProcessorSettings postProcessorSettings, UnityEditor.Modules.BuildPostProcessArgs args) (at /Users/bokken/build/output/unity/unity/PlatformDependent/iPhonePlayer/Extensions/Common/BuildPostProcessor.cs:695)
UnityEditor.iOS.iOSBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args) (at /Users/bokken/build/output/unity/unity/PlatformDependent/iPhonePlayer/Extensions/Common/ExtensionModule.cs:45)
Rethrow as BuildFailedException: Exception of type ‘UnityEditor.Build.BuildFailedException’ was thrown.
UnityEditor.iOS.iOSBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args) (at /Users/bokken/build/output/unity/unity/PlatformDependent/iPhonePlayer/Extensions/Common/ExtensionModule.cs:49)
UnityEditor.Modules.DefaultBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args, UnityEditor.BuildProperties& outProperties) (at /Users/bokken/build/output/unity/unity/Editor/Mono/Modules/DefaultBuildPostprocessor.cs:28)
UnityEditor.PostprocessBuildPlayer.Postprocess (UnityEditor.BuildTargetGroup targetGroup, UnityEditor.BuildTarget target, System.Int32 subtarget, System.String installPath, System.String companyName, System.String productName, System.Int32 width, System.Int32 height, UnityEditor.BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport report) (at /Users/bokken/build/output/unity/unity/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:370)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:189)
[/code]

Build completed with a result of 'Failed' in 65 seconds (64747 ms)

I have the same problem in unity cloud build