AutoMapper: System.NullReferenceException: iOS only

Trying to map an Ilist of Interfaces to an IList of implementations I am getting a Nullreference error. However I only receive this on iOS the same implementation works fine on Android. The error does not occur at the mapping the mapping goes through fine and the resulting collection appears to be fine. However after the event (onappearing) in which the map occurs completes only then does this error get raised. Presumably this is a Async method that doesnt complete till later a dispose or some other threading issue.

Downgrading to Automapper 4.2.1 resolves the error.

Good Luck - if this is half as hard to fix as it was to track down its going to be a pain for someone.

** Version Using AutoMapper" version=“5.1.1” targetFramework=“portable45-net45+win8+wpa81” on iOS

** Error System.NullReferenceException: Object reference not set to an instance of an object

** Code var items = DataMapper.Mapper.Map<IList<IDailyChallenge>, IList<DailyChallengeViewModel>>(dailychallenges);

** Stack Trace at Microsoft.Scripting.Interpreter.LoopCompiler.VisitVariable (System.Linq.Expressions.ParameterExpression node, Microsoft.Scripting.Ast.ExpressionAccess access) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/LoopCompiler.cs:279 at Microsoft.Scripting.Interpreter.LoopCompiler.VisitParameter (System.Linq.Expressions.ParameterExpression node) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/LoopCompiler.cs:271 at System.Linq.Expressions.ParameterExpression.Accept (System.Linq.Expressions.ExpressionVisitor visitor) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Ast/ParameterExpression.cs:118 at System.Linq.Expressions.ExpressionVisitor.Visit (System.Linq.Expressions.Expression node) [0x00006] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:57 at System.Linq.Expressions.ExpressionVisitor.VisitMethodCall (System.Linq.Expressions.MethodCallExpression node) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:414 at System.Linq.Expressions.MethodCallExpression.Accept (System.Linq.Expressions.ExpressionVisitor visitor) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Ast/MethodCallExpression.cs:106 at System.Linq.Expressions.ExpressionVisitor.Visit (System.Linq.Expressions.Expression node) [0x00006] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:57 at System.Linq.Expressions.ExpressionVisitor.VisitBinary (System.Linq.Expressions.BinaryExpression node) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:198 at Microsoft.Scripting.Interpreter.LoopCompiler.VisitBinary (System.Linq.Expressions.BinaryExpression node) [0x000b4] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/LoopCompiler.cs:254 at System.Linq.Expressions.BinaryExpression.Accept (System.Linq.Expressions.ExpressionVisitor visitor) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Ast/BinaryExpression.cs:331 at System.Linq.Expressions.ExpressionVisitor.Visit (System.Linq.Expressions.Expression node) [0x00006] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:57 at System.Linq.Expressions.ExpressionVisitor.VisitConditional (System.Linq.Expressions.ConditionalExpression node) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:250 at System.Linq.Expressions.ConditionalExpression.Accept (System.Linq.Expressions.ExpressionVisitor visitor) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Ast/ConditionalExpression.cs:93 at System.Linq.Expressions.ExpressionVisitor.Visit (System.Linq.Expressions.Expression node) [0x00006] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:57 at System.Linq.Expressions.ExpressionVisitor.VisitLoop (System.Linq.Expressions.LoopExpression node) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:378 at System.Linq.Expressions.LoopExpression.Accept (System.Linq.Expressions.ExpressionVisitor visitor) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Ast/LoopExpression.cs:82 at System.Linq.Expressions.ExpressionVisitor.Visit (System.Linq.Expressions.Expression node) [0x00006] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/System.Core/Microsoft/Scripting/Ast/ExpressionVisitor.cs:57 at Microsoft.Scripting.Interpreter.LoopCompiler.CreateDelegate () [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/LoopCompiler.cs:82 at Microsoft.Scripting.Interpreter.EnterLoopInstruction.Compile (System.Object frameObj) [0x00074] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/ControlFlowInstructions.cs:601 at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context (System.Object state) [0x0000e] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:1304 at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x0008d] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/threading/executioncontext.cs:957 at System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/threading/executioncontext.cs:904 at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem () [0x0002a] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:1281 at System.Threading.ThreadPoolWorkQueue.Dispatch () [0x00096] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:854 at ObjCRuntime.Runtime.ThreadPoolDispatcher (System.Func`1[TResult] callback) [0x00006] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/src/ObjCRuntime/Runtime.cs:238 at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback () [0x0000c] in /Users/builder/data/lanes/3426/6c3fee4d/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:1206