Well, i have the same problem, but not much info unfortunately:
Assertion failed on expression: '!go.TestHideFlag(Object::kNotEditable)'
0x0000000141415828 (Unity) StackWalker::GetCurrentCallstack
0x000000014141BCD6 (Unity) StackWalker::ShowCallstack
0x00000001412FF55B (Unity) GetStacktrace
0x00000001401432FE (Unity) DebugStringToFile
0x0000000140E21E8A (Unity) AddComponentToPrefabObjectNotification
0x00000001408FC336 (Unity) InvokeAddComponentCallback
0x00000001408F3F2D (Unity) AddComponentUnchecked
0x00000001408F3C7D (Unity) AddComponent
0x0000000140B5EA2F (Unity) MonoAddComponentWithType
0x000000014178CDB7 (Unity) GameObject_CUSTOM_Internal_AddComponentWithType
0x0000000046B4C899 (Mono JIT Code) (wrapper managed-to-native) UnityEngine.GameObject:Internal_AddComponentWithType (UnityEngine.GameObject,System.Type) (at ?)
0x0000000046B4C6F3 (Mono JIT Code) [GameObject.bindings.cs:221] UnityEngine.GameObject:AddComponent (System.Type) (at ?)
0x0000000046CE8913 (Mono JIT Code) [GameObject.bindings.cs:226] UnityEngine.GameObject:AddComponent<T_REF> () (at ?)
0x0000000048E91C6B (Mono JIT Code) [PlayMakerFSM.cs:469] PlayMakerFSM:GetEventHandlerComponent<T_REF> (UnityEngine.GameObject) (at ?)
0x0000000048E9191B (Mono JIT Code) [PlayMakerFSM.cs:447] PlayMakerFSM:AddEventHandlerComponent<T_REF> () (at ?)
0x0000000048E70B73 (Mono JIT Code) [PlayMakerFSM.cs:388] PlayMakerFSM:AddEventHandlerComponents () (at ?)
0x0000000082EF217B (Mono JIT Code) [PlayMakerFSM.cs:226] PlayMakerFSM:Preprocess () (at ?)
0x0000000048F0024B (Mono JIT Code) [PlayMakerBuildCallbacks.cs:34] HutongGames.PlayMakerEditor.PlayMakerBuildCallbacks:OnPostprocessScene () (at ?)
0x0000000039B8E85D (Mono JIT Code) (wrapper runtime-invoke) object:runtime_invoke_void (object,intptr,intptr,intptr) (at ?)
0x000007FECDD2BE4B (mono-2.0-bdwgc) [mini-runtime.c:2809] mono_jit_runtime_invoke
0x000007FECDCB1E32 (mono-2.0-bdwgc) [object.c:2919] do_runtime_invoke
0x000007FECDCBB012 (mono-2.0-bdwgc) [object.c:3071] mono_runtime_invoke_checked
0x000007FECDCBB7A9 (mono-2.0-bdwgc) [object.c:5262] mono_runtime_try_invoke_array
0x000007FECDCBAFA6 (mono-2.0-bdwgc) [object.c:5140] mono_runtime_invoke_array_checked
0x000007FECDC5FED4 (mono-2.0-bdwgc) [icall.c:3358] ves_icall_InternalInvoke
0x000000003865C6B6 (Mono JIT Code) (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&) (at ?)
0x000000003865B0DB (Mono JIT Code) System.Reflection.MonoMethod:Invoke (object,System.Reflection.BindingFlags,System.Reflection.Binder,object[],System.Globalization.CultureInfo) (at ?)
0x0000000038AA35BF (Mono JIT Code) System.Reflection.MethodBase:Invoke (object,object[]) (at ?)
0x0000000048EF5643 (Mono JIT Code) [BuildPipelineInterfaces.cs:163] UnityEditor.Build.BuildPipelineInterfaces/AttributeCallbackWrapper:OnProcessScene (UnityEngine.SceneManagement.Scene,UnityEditor.Build.Reporting.BuildReport) (at ?)
0x0000000048EEBB10 (Mono JIT Code) [BuildPipelineInterfaces.cs:387] UnityEditor.Build.BuildPipelineInterfaces/<OnSceneProcess>c__AnonStorey1:<>m__1 (UnityEditor.Build.IProcessSceneWithReport) (at ?)
0x0000000048EEB682 (Mono JIT Code) [BuildPipelineInterfaces.cs:356] UnityEditor.Build.BuildPipelineInterfaces:InvokeCallbackInterfacesPair<T1_REF, T2_REF> (System.Collections.Generic.List`1<T1_REF>,System.Action`1<T1_REF>,System.Collections.Generic.List`1<T2_REF>,System.Action`1<T2_REF>,bool) (at ?)
0x0000000048EEA693 (Mono JIT Code) [BuildPipelineInterfaces.cs:385] UnityEditor.Build.BuildPipelineInterfaces:OnSceneProcess (UnityEngine.SceneManagement.Scene,UnityEditor.Build.Reporting.BuildReport) (at ?)
0x0000000048EEA90E (Mono JIT Code) (wrapper runtime-invoke) <Module>:runtime_invoke_void_Scene_object (object,intptr,intptr,intptr) (at ?)
0x000007FECDD2BE4B (mono-2.0-bdwgc) [mini-runtime.c:2809] mono_jit_runtime_invoke
0x000007FECDCB1E32 (mono-2.0-bdwgc) [object.c:2919] do_runtime_invoke
0x000007FECDCBAE3F (mono-2.0-bdwgc) [object.c:2966] mono_runtime_invoke
0x0000000140C02AAA (Unity) scripting_method_invoke
0x0000000140BF30BA (Unity) ScriptingInvocation::Invoke
0x0000000140BED0F5 (Unity) ScriptingInvocation::Invoke<void>
0x00000001401D51C1 (Unity) Scripting::UnityEditor::Build::BuildPipelineInterfacesProxy::OnSceneProcess
0x000000014098DD76 (Unity) ProcessSceneBeforeExport
0x0000000140D61E76 (Unity) BuildCopyGameScene
0x0000000140D684FA (Unity) BuildPlayerData
0x0000000140D74D02 (Unity) DoBuildPlayer_Build
0x0000000140D747A3 (Unity) DoBuildPlayer
0x0000000140D66AB8 (Unity) BuildPlayer
0x000000014228977A (Unity) BuildPipeline::BuildPlayerInternalNoCheck
0x0000000142287734 (Unity) BuildPipeline_CUSTOM_BuildPlayerInternalNoCheck
0x00000000550A3423 (Mono JIT Code) (wrapper managed-to-native) UnityEditor.BuildPipeline:BuildPlayerInternalNoCheck (string[],string,string,UnityEditor.BuildTargetGroup,UnityEditor.BuildTarget,UnityEditor.BuildOptions,bool) (at ?)
0x00000000550A28F3 (Mono JIT Code) [BuildPlayerWindowBuildMethods.cs:172] UnityEditor.BuildPlayerWindow/DefaultBuildMethods:BuildPlayer (UnityEditor.BuildPlayerOptions) (at ?)
0x00000000112BAE4B (Mono JIT Code) [BuildPlayerWindowBuildMethods.cs:97] UnityEditor.BuildPlayerWindow:CallBuildMethods (bool,UnityEditor.BuildOptions) (at ?)
0x0000000052CCC9FB (Mono JIT Code) [BuildPlayerWindow.cs:174] UnityEditor.BuildPlayerWindow:BuildPlayerAndRun (bool) (at ?)
0x0000000052CCC76B (Mono JIT Code) [BuildPlayerWindow.cs:168] UnityEditor.BuildPlayerWindow:BuildPlayerAndRun () (at ?)
0x0000000049F3A855 (Mono JIT Code) (wrapper runtime-invoke) object:runtime_invoke_void (object,intptr,intptr,intptr) (at ?)
0x000007FECDD2BE4B (mono-2.0-bdwgc) [mini-runtime.c:2809] mono_jit_runtime_invoke
0x000007FECDCB1E32 (mono-2.0-bdwgc) [object.c:2919] do_runtime_invoke
0x000007FECDCBAE3F (mono-2.0-bdwgc) [object.c:2966] mono_runtime_invoke
0x0000000140BEF93B (Unity) CallStaticMonoMethod
0x0000000140BEF6CB (Unity) CallStaticMonoMethod
0x0000000140D6DE0F (Unity) BuildPlayerWithLastSettings
0x0000000140DDE6BC (Unity) FileMenu::Execute
0x00000001412AC5DD (Unity) MenuController::ExecuteMenuItem
0x00000001414989FC (Unity) ProcessMainWindowMessages
0x00000001414694CF (Unity) ContainerWindow::ContainerWndProc
0x00000000774C9BBD (USER32) TranslateMessageEx
0x00000000774C98C2 (USER32) TranslateMessage
0x000000014149836F (Unity) MainMessageLoop
0x0000000141499E66 (Unity) WinMain
0x000000014247DE8A (Unity) __scrt_common_main_seh
0x00000000775C59CD (kernel32) BaseThreadInitThunk
0x00000000776FA561 (ntdll) RtlUserThreadStart
Any ideas? I was supposed to launch a demo this weekend, this is a big time problem. I see Jean posted the thread that i also found, but i don't see where or how am i editing prefab instead of instance, nor how can i find the perpetrator.
I'll start by eliminating all playmaker errors and warnings...