Exception in callback: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.MissingMethodException: Method not found: 'UnityEngine.Mesh.Clear'.

  at Vuforia.BackgroundPlaneAbstractBehaviour.OnTrackablesUpdated () [0x00000] in <filename unknown>:0 

  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (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) [0x000d0] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222 

  --- 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) [0x000eb] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232 

  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115 

  at System.Delegate.DynamicInvokeImpl (System.Object[] args) [0x000b9] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Delegate.cs:443 

  at System.MulticastDelegate.DynamicInvokeImpl (System.Object[] args) [0x00018] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/MulticastDelegate.cs:71 

  at System.Delegate.DynamicInvoke (System.Object[] args) [0x00000] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Delegate.cs:415 

  at Vuforia.DelegateHelper.InvokeDelegate (System.Delegate action, System.Object[] args) [0x00000] in <filename unknown>:0 

UnityEngine.Debug:LogError(Object)

Vuforia.DelegateHelper:InvokeDelegate(Delegate, Object[])

Vuforia.DelegateHelper:InvokeWithExceptionHandling(Action)

Vuforia.VuforiaARController:UpdateStatePrivate(Boolean, Boolean)

Vuforia.VuforiaARController:UpdateState(Boolean, Boolean)

Vuforia.DigitalEyewearARController:Update()

System.Delegate:DynamicInvoke(Object[])

Vuforia.DelegateHelper:InvokeDelegate(Delegate, Object[])

Vuforia.DelegateHelper:InvokeWithExceptionHandling(Action)

Vuforia.VuforiaAbstractBehaviour:Update()