Can't launch html5 project 4.18.1(ue4 starter scene just plane and sun sky)

Can’t launch html5 project 4.18.1(ue4 starter scene just plane and sun sky) on win 7
I tested on diferent computer just ue4 4.18.1 just starter scene and it works.

Error firefox quantum 64 bit:

Expression (InOuter || (InClass == UPackage::StaticClass() && InName != NAME_None)) failed in D:\Build++UE4+Release-4.18+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:2268!
Check console for details.

Error after all third party plugins off in ue4
firefox quantum 64 bit:

Expression (Key.IsValid()) failed in D:\Build++UE4+Release-4.18+Compile\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:6103!
Check console for details.

Hello amk-art,

I was unable to reproduce the issue you are experiencing on our end. I have a couple questions to help narrow down the issue you are having.

  1. Can you post the DxDiag of the machine where this issue occurs?
  2. Does this issue also happen if you try and launch HTML5 for Chrome on your Win 7 machine?
  3. Does this issue only occur for you for 4.18?
  4. Can you provide the full cook log for the launch to HTML5?


It seems i messed up with my firefox because i tested on different machine and works without problem.

Hello again,

Is this issue no longer occurring for you?



We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will follow up.