Xamarin Studio / VS for Mac Storyboard not opening

Question

I bought a new MacBook Pro for developing an iOS Universal App. Before I have sold my old one, I pushed my code to a BitBucket Repository.

Now I have installed VS for Mac and Xamarin Studio and pulled the source code from bitbucket. Everything is working fine (building, debugging, etc.) but designing in storyboard designer wont work.

I am getting following exception:

    [2017-07-25 15:55:16.3] ERROR: EnsureSession (counter 1): MonoTouch.Design.Client.DesignerRemoteException: System.NotSupportedException: Could not parse xml
    at MonoTouch.Design.Parser.Parse (MonoTouch.Design.ParseContext context) in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:220
    at MonoTouch.Design.UIKitParser.Parse (MonoTouch.Design.ParseContext context) in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:205
    at MonoTouch.Design.Server.SessionController.LoadXmlCore (MonoTouch.Design.ParseContext ctx) in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/SessionController.cs:332
    at MonoTouch.Design.Server.SessionController.LoadXml (System.Xml.Linq.XElement xml, System.Boolean freezeMisplacements, System.String[] viewsToHide) in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/SessionController.cs:304
    at MonoTouch.Design.Server.SessionController.LoadFullXml (System.Xml.Linq.XElement xml, System.Boolean freezeMisplacements, System.String[] viewsToHide) in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/SessionController.cs:208
    at MonoTouch.Design.Server.CommandListener.LoadXml (MonoTouch.Design.CommandRequest untypedRequest, MonoTouch.Design.Server.SessionController controller) in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/Connection/CommandListener.cs:207
    at MonoTouch.Design.Server.Router.Route (MonoTouch.Design.SessionCommandRequest request, MonoTouch.Design.Server.SessionController controller) in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/Connection/Router.cs:49
    at MonoTouch.Design.Server.CommandListener+<HandleRequestAsync>c__async1.MoveNext () in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/Connection/CommandListener.cs:99
  at MonoTouch.Design.Client.ServerProcessConnection.SendRequest (MonoTouch.Design.CommandRequest req, System.Boolean throwIfNotRunning) [0x00059] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Client/Connection/ServerProcessConnection.cs:234 
  at MonoTouch.Design.Client.ServerProcessConnection.SendRequest[TResponse] (MonoTouch.Design.CommandRequest req, System.Boolean throwIfNotRunning) [0x00000] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Client/Connection/ServerProcessConnection.cs:243 
  at MonoTouch.Design.Client.ServerProcessConnection.PostXml (MonoTouch.Design.DesignSession session, System.String xml, System.String[] viewsToHide) [0x00014] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Client/Connection/ServerProcessConnection.cs:186 
  at MonoTouch.Design.Client.ServerProcessConnection.PostXml (MonoTouch.Design.DesignSession session, System.Xml.Linq.XElement fullStoryboard, System.Xml.Linq.XElement[] partialElements, System.Boolean freezeMisplacements, System.String[] viewsToHide) [0x000c0] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Client/Connection/ServerProcessConnection.cs:165 
  at MonoTouch.Design.Client.IPhoneDesignerSession+<RenderXmlWithPartialReloadRetry>c__async4+<RenderXmlWithPartialReloadRetry>c__AnonStorey16.<>m__0 (MonoTouch.Design.Client.ServerProcessConnection c) [0x00000] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Client/IPhoneDesignerSession.cs:652 
  at MonoTouch.Design.Client.IPhoneDesignerSession+<EnsureSession>c__AnonStorey3B`1[TResult].<>m__0 () [0x0012d] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Client/IPhoneDesignerSession.cs:1989 

According to the exception my xml (storyboard) is invalid and could not be parsed. Somehow I was able to open the storyboard on my old MacBook (6 months ago). It is also possible to open the storyboard through the XCode Interface Builder.

Errors happening in detail:

    com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.310 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Could not find MonoTouch.Design.Storyboard.useTraitCollections

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.310 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Could not find MonoTouch.Design.Storyboard.colorMatched

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.310 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Could not find MonoTouch.Design.Storyboard.device

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.312 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Could not find MonoTouch.Design.ProxiedPageViewController.storyboardIdentifier

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.313 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Could not find MonoTouch.Design.ProxiedViewController.storyboardIdentifier

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.317 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Could not find MonoTouch.Design.ProxiedLabel.usesAttributedText

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.325 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Could not parse UIColor specified with the following data: '<color key="NSColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace" />'

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.331 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Error in type parser for: UIKit.UIFont
System.NotImplementedException: <font key="NSFont" metaFont="system" size="200" />
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.InvokeWorker (System.Object[] args) [0x00024] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:263 
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.Invoke (System.Object[] args) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:239 
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.Run (Microsoft.Scripting.Interpreter.InterpretedFrame frame) [0x0003b] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:289 
  at Microsoft.Scripting.Interpreter.Interpreter.Run (Microsoft.Scripting.Interpreter.InterpretedFrame frame) [0x0001b] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Interpreter.cs:126 

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.331 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: Error in type parser for: {0}
System.NotImplementedException: <font key="NSFont" metaFont="system" size="200" />
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.InvokeWorker (System.Object[] args) [0x00024] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:263 
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.Invoke (System.Object[] args) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:239 
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.Run (Microsoft.Scripting.Interpreter.InterpretedFrame frame) [0x0003b] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:289 
  at Microsoft.Scripting.Interpreter.Interpreter.Run (Microsoft.Scripting.Interpreter.InterpretedFrame frame) [0x0001b] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Interpreter.cs:126 

com.xamarin.MTHosting.aa6984471.stderr: 2017-07-25 15:55:16.336 MonoTouchDesignServerUnified[2229:79606] [2017-07-25 15:55:16.3] ERROR: UNHANDLED EXCEPTION:
System.NotSupportedException: Could not parse xml ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NotImplementedException: <font key="NSFont" metaFont="system" size="200" />
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.InvokeWorker (System.Object[] args) [0x00024] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:263 
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.Invoke (System.Object[] args) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:239 
  at Microsoft.Scripting.Interpreter.MethodInfoCallInstruction.Run (Microsoft.Scripting.Interpreter.InterpretedFrame frame) [0x0003b] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Instructions/CallInstruction.cs:289 
  at Microsoft.Scripting.Interpreter.Interpreter.Run (Microsoft.Scripting.Interpreter.InterpretedFrame frame) [0x0001b] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/dlr/Runtime/Microsoft.Dynamic/Interpreter/Interpreter.cs:126 
   --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00050] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:313 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/reflection/methodbase.cs:229 
  at MonoTouch.Design.Parser.ParseElements (MonoTouch.Design.ParseContext context, System.Object result) [0x000ff] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:312 
  at MonoTouch.Design.Parser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0002c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:267 
  at MonoTouch.Design.UIKitParser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0000b] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:1392 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context, System.Object result, Xamarin.Designer.ProxiedException error) [0x00114] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:358 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context) [0x0005a] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:240 
  at MonoTouch.Design.Parser.ParseElement (System.Object result, MonoTouch.Design.ParseContext context) [0x00088] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:1061 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00038] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:305 
   --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00050] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:313 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/reflection/methodbase.cs:229 
  at MonoTouch.Design.Parser.ParseElements (MonoTouch.Design.ParseContext context, System.Object result) [0x000ff] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:312 
  at MonoTouch.Design.Parser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0002c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:267 
  at MonoTouch.Design.UIKitParser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0000b] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:1392 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context, System.Object result, Xamarin.Designer.ProxiedException error) [0x00114] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:358 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context) [0x0005a] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:240 
  at MonoTouch.Design.Parser.ParseElement (MonoTouch.Design.ProxiedView model, MonoTouch.Design.ParseContext context) [0x00048] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:779 
  at MonoTouch.Design.UIKitParser.ParseElement (MonoTouch.Design.ProxiedView model, MonoTouch.Design.ParseContext context) [0x00004] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:2014 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00038] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:305 
   --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00050] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:313 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/reflection/methodbase.cs:229 
  at MonoTouch.Design.Parser.ParseElements (MonoTouch.Design.ParseContext context, System.Object result) [0x000ff] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:312 
  at MonoTouch.Design.Parser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0002c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:267 
  at MonoTouch.Design.UIKitParser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0000b] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:1392 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context, System.Object result, Xamarin.Designer.ProxiedException error) [0x00114] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:358 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context) [0x0005a] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:240 
  at MonoTouch.Design.Parser.ParseElement (MonoTouch.Design.ProxiedViewController model, MonoTouch.Design.ParseContext context) [0x000d4] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:735 
  at MonoTouch.Design.UIKitParser.ParseElement (MonoTouch.Design.ProxiedViewController model, MonoTouch.Design.ParseContext context) [0x00054] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:1882 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00038] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:305 
   --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00050] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:313 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/reflection/methodbase.cs:229 
  at MonoTouch.Design.Parser.ParseElements (MonoTouch.Design.ParseContext context, System.Object result) [0x000ff] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:312 
  at MonoTouch.Design.Parser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0002c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:267 
  at MonoTouch.Design.UIKitParser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0000b] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:1392 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context, System.Object result, Xamarin.Designer.ProxiedException error) [0x00114] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:358 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context) [0x0005a] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:240 
  at MonoTouch.Design.Parser.ParseElement (MonoTouch.Design.Scene scene, MonoTouch.Design.ParseContext context) [0x0009f] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:677 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00038] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:305 
   --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00050] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:313 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/reflection/methodbase.cs:229 
  at MonoTouch.Design.Parser.ParseElements (MonoTouch.Design.ParseContext context, System.Object result) [0x000ff] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:312 
  at MonoTouch.Design.Parser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0002c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:267 
  at MonoTouch.Design.UIKitParser.ParseElementsAndAttributes (MonoTouch.Design.ParseContext context, System.Object result) [0x0000b] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:1392 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context, System.Object result, Xamarin.Designer.ProxiedException error) [0x00114] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:358 
  at MonoTouch.Design.Parser.ParseCore (MonoTouch.Design.ParseContext context) [0x0005a] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:240 
  at MonoTouch.Design.Parser.ParseElement (MonoTouch.Design.Storyboard sb, MonoTouch.Design.ParseContext context) [0x0004c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:856 
  at MonoTouch.Design.UIKitParser.ParseElement (MonoTouch.Design.Storyboard sb, MonoTouch.Design.ParseContext context) [0x00004] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:1584 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00038] in /Users/builder/data/lanes/1381/d2cbd993/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:305 
   --- End of inner exception stack trace ---
  at MonoTouch.Design.Parser.Parse (MonoTouch.Design.ParseContext context) [0x00035] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Shared/Parser.cs:220 
  at MonoTouch.Design.UIKitParser.Parse (MonoTouch.Design.ParseContext context) [0x00013] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/TypeSystem/Loader.cs:205 
  at MonoTouch.Design.Server.SessionController.LoadXmlCore (MonoTouch.Design.ParseContext ctx) [0x00019] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/SessionController.cs:332 
  at MonoTouch.Design.Server.SessionController.LoadXml (System.Xml.Linq.XElement xml, System.Boolean freezeMisplacements, System.String[] viewsToHide) [0x0004d] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/SessionController.cs:304 
  at MonoTouch.Design.Server.SessionController.LoadFullXml (System.Xml.Linq.XElement xml, System.Boolean freezeMisplacements, System.String[] viewsToHide) [0x0000c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/SessionController.cs:208 
  at MonoTouch.Design.Server.CommandListener.LoadXml (MonoTouch.Design.CommandRequest untypedRequest, MonoTouch.Design.Server.SessionController controller) [0x001c6] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/Connection/CommandListener.cs:207 
  at MonoTouch.Design.Server.Router.Route (MonoTouch.Design.SessionCommandRequest request, MonoTouch.Design.Server.SessionController controller) [0x0001c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/Connection/Router.cs:49 
  at MonoTouch.Design.Server.CommandListener+<HandleRequestAsync>c__async1.MoveNext () [0x0011c] in /Users/builder/data/lanes/4470/6c2f6737/source/md-addins/Xamarin.Designer.iOS/MonoTouch.Design.Server/Connection/CommandListener.cs:99 

Any suggestions how to fix this? I really dont want to start redesigning my app.

Thanks!

Answer 1

although advise from Andre is good one, it still not valid for many cases. I had an old project created 3 years ago, adding a new storyboard into this project returns this error. for example, i had errors like useTraitCollections and colorMatched couldnt be found. I added them manually but still was returning same errors. I found a working storyboard code on another project and copied into my not working one. This fixes problem first then you can modify this storyboard.

Answer 2

After a long time, and without help from Xamarin i figured out where the problem was located.

Steps I've made to solve the problem:

1. Copy the whole error-stack to an editor
2. Start reading from the bottom (as usual)
3. Figure out where the last exception happend
4. Comment the corresponding element / attribute in xml out
5. Repeat step 2 -> 4 until no error message appears

In my case there were several invalid elements, such as:

    2017-11-30 23:50:42.8] ERROR: Error in type parser for: UIKit.UIFont
System.NotImplementedException: <font key="NSFont" metaFont="smallSystem" />

and

com.xamarin.MTHosting.3d875c911.stderr: 2017-11-30 23:45:45.638 MonoTouchDesignServerUnified[64451:979709] [2017-11-30 23:45:45.6] ERROR: Error in type parser for: UIKit.UIFont
System.NotImplementedException: <font key="NSFont" metaFont="cellTitle" />

So I just opened my storyboard with the "Sourcecode editor" and commented those elements out.

And finally, I can edit my storyboard again.

Answer 3

The issue is that Xcode interface builder adds an additional attribute called 'device' which specifies the initial device setup. Open the .xib using source code editor and simply remove the 'device' attribute and it should work fine.

Read more - Bug 58804