GUI Window tries to begin rendering while something else has not finished rendering! Either you have a recursive OnGUI rendering, or previous OnGUI did not clean up properly.
UnityEditor.EditorUtility:smile:isplayDialog(String, String, String)
Vuforia.EditorClasses.UnityPlayModeEditorUtility:LoadAndParseWebcamProfiles(String)
Vuforia.WebCamProfile:.ctor()
Vuforia.EditorClasses.WebCamEditor:smile:rawInspectorGUI()
Vuforia.EditorClasses.VuforiaAbstractConfigurationEditor:OnInspectorGUI()
UnityEditor.DockArea:OnGUI()
Exception occurred when trying to parse web cam profile file: Could not parse webcam profile: 640480640640480640
UnityEngine.Debug:LogError(Object)
Vuforia.EditorClasses.UnityPlayModeEditorUtility:LoadAndParseWebcamProfiles(String)
Vuforia.WebCamProfile:.ctor()
Vuforia.EditorClasses.WebCamEditor:smile:rawInspectorGUI()
Vuforia.EditorClasses.VuforiaAbstractConfigurationEditor:OnInspectorGUI()
UnityEditor.EditorUtility:smile:isplayDialog(String, String, String)
Vuforia.EditorClasses.UnityPlayModeEditorUtility:LoadAndParseWebcamProfiles(String)
Vuforia.WebCamProfile:.ctor()
Vuforia.EditorClasses.WebCamEditor:smile:rawInspectorGUI()
Vuforia.EditorClasses.VuforiaAbstractConfigurationEditor:OnInspectorGUI()
UnityEditor.DockArea:OnGUI()
InvalidOperationException: Operation is not valid due to the current state of the object
System.Collections.Generic.Stack`1[System.Boolean].Pop ()
UnityEditor.EditorGUI.EndDisabledGroup () (at /home/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:211)
UnityEditor.InspectorWindow.DrawEditor (UnityEditor.Editor editor, Int32 editorIndex, Boolean rebuildOptimizedGUIBlock, System.Boolean& showImportedObjectBarNext, UnityEngine.Rect& importedObjectBarRect) (at /home/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1254)
UnityEditor.InspectorWindow.DrawEditors (UnityEditor.Editor[ ] editors) (at /home/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1028)
UnityEditor.InspectorWindow.OnGUI () (at /home/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:352)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[ ] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
UnityEditor.EditorUtility:smile:isplayDialog(String, String, String)
Vuforia.EditorClasses.UnityPlayModeEditorUtility:LoadAndParseWebcamProfiles(String)
Vuforia.WebCamProfile:.ctor()
Vuforia.EditorClasses.WebCamEditor:smile:rawInspectorGUI()
Vuforia.EditorClasses.VuforiaAbstractConfigurationEditor:OnInspectorGUI()
UnityEditor.DockArea:OnGUI()
many other error also occurs.