I have a project that is a architectural walk through. I am trying to export it to HTML5. I can launch it on my computer and run through the level there. I have gone through the https://docs.unrealengine.com/en-us/...GettingStarted documentation and do not seem to have any issues exporting to HTML5. However, after starting the HTMLLaunchHelper.exe and opening localhost:8000/.html I receive an error, the text of the error is:
Expression (InOuter || (InClass == UPackage::StaticClass() && InName != NAME_None)) failed in D:\Build++UE4\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp:2345!
Check console for details.
If I click OK the web page adds ‘Initializing Engine…’ and just sit there with spinning arrows.
I have tried in both Chrome and Edge, same results. I have tried in Chrome on another computer, same results.
I have exactly the same issue, were you able to solve this?
It seems to have started with the latest update of UE 4.21.1, UE4.20 it is still working fine.
I have submitted a bug to Unreal. I have just finished replying to their request for more information, I gave them in depth details of the issue I experienced. They say they couldn’t replicate the issue. I added this page in my reply to them saying that I am not the only one having the issue.
It took about a week for them to reply to my initial bug submission so no telling how long it will take for them to follow up. If/when they do I will post their response here.
This is the response I received from my bug submission, after giving more information and telling them that you are having the same issue:
Thank you for all of that information. Unfortunately I can still not reproduce the issue, it just is not occurring for me. I spoke to our primary HTML5 developer and they mentioned attempting Firefox instead of Chrome as Firefox is usually quicker with Launch On from UE4 in particular, so he’s curious to see if there may be a difference in this case. Please let me know your results and I’ll relay it to them to see if they have any ideas.
note to self: i’m adding the following link for reference…
seems (so far) when there’s a subversion update things break on HTML5. i would like to get to the bottom of this.
winthrod, i believe you were in contact with matt, yes? i’m the html5 dev he mentioned.
internal testing has shown that your zipped uproject builds fine in Developer, Shipping and Shipping For Distribution. so i’m wondering what you and bvvintecc might have on your development environment.
please post what are your PC/Mac specs here.
and if you wish, please PM me your “Editor Session Log” and “Build/Cook/Package” logs. to find your logs, please see:
Yes, I can launch from the editor to my computer and play the level just fine. And if I package it for Windows 64-bit, I can launch and play just fine there. The issue only comes up when when trying to launch from the editor to Chrome, or Edge, or trying to package HTML5 and running the localhost web server.
I have a Dell Precision M7720, running Windows 10 Pro, Xeon Processor, 32 GB RAM, Intel HD Graphics P630 on board with discrete Quadro P4000 video card with 8 GB of RAM.
I will be PM’ing you the Editor Session and Build/Cook/Package logs shortly.
I just finished sending logs and machine info to Nick above. Hopefully he can determine what is happening.
One thing I did for testing was created a basic FPS shooter project with no starter content in Engine 4.20.3. I was able to launch in Chrome from the Editor just fine.
I then created the exact same project, basic FPS shooter with no starter content, in Engine 4.21.1. Trying to launch Chrome from the editor gave me the error. Only difference between the two is the engine version.
I sent a link to Bug Submission of my project file. Their response was:
“internal testing has shown that your zipped uproject builds fine in Developer, Shipping and Shipping For Distribution. so i’m wondering what you and bvvintecc might have on your development environment.”
I haven’t modified my development environment - at least not that I am aware of.
Today I received a new desktop computer. I did a clean install of windows 10 professional. Next thing I did was installing ue 4.21.1. During setup it asked for installation of VS2017 which I did. Next I installed Chrome. Next up, I created a blank C++ project and tried to launch for HTML5 chrome.
And I got the same error again as on my other system.
If you want, you can e-mail me on and we can setup a teamviewer session so you can investigate this issue.
I had the same issue a while ago and did not know what to do until I found a notice in the browsers console window, regarding errors produced by some plugins. For me it was the Unreal Studio plugins ‘MDL/AxF Importer’, ‘Variant Manager’, ‘Variant Manager Content’ and ‘Sample Mesh Reconstructor’, if I remember correctly. Once disabled, I exported it using Shipping Build and it worked.
Bas3008,
I had some hope that this was the solution. I disabled the pluggins you mentioned and tried launching Chrome from the Editor. I didn’t get an error but Chrome crashed after about two seconds. I then tried exporting to HTML5 and launching a localhost. I received the same error, it is attached.
Then I noticed that most of the plugins were Beta, so I went through and disable most of the beta plugins and tried again. Again, Chrome crashed in about a second after launch. I have attached screenshot of the Output Log.
Based on your answer, I disabled some of the experimental plugings + variant manager content + sample mesh reconstructor. The other 2 plugins, I couldn’t find in the plugin manager.
disabled ‘Variant Manager’, ‘Variant Manager Content’ and ‘Sample Mesh Reconstructor’ and got it working, couldn’t find MDL/AxF Importer for some reason → error disappeared
On my laptop:
the Sample Mesh Reconstructor was already disabled
first disabled the variant manager and variant manager content, launced, but the error persisted
next disabled MDL/AxF importer extra, the error disappeared
My final conclusion would be you need to disable them all as Bas proposed.
Have you tried packaging with ‘Shipping’? For me, the Unreal Studio plugins were the cause of the error, maybe you’re also using some additional plugins?
Aside from that, I suggest to try the game in Firefox, as it might not crash like Chrome and you may be able to gain more information in the Browser Console.
this is an excellent thread – thank you everyone for helping hunt this down. with HTML5 WASM multithreading work getting plowed in for the 4.22 merge deadline, i wasn’t able to help you all with this. but, i’m glad you all were able to narrow down the issues.
i will ask around to see who owns those plugins to ensure those get blacklisted for HTML5. thanks again!
I apologize for not getting back to this earlier, had to replace my hard drive.
I hate to be the thrower of wrinkles in here but I have additional information to add. I was able to get my test fps project running in HTML5 by disabling the pluggins suggested above. However, after opening my archvis project, the one that started me on this journey, it crashed on me - even after disabling the above mentions plugins.
Needless to say this frustrated me greatly. I had disabled a number of beta plugins previously on the fps project, I was hoping that one of those was causing the crash. So, I documented all the current plugins for Unreal - all 190 some odd of them in a spreadsheet. I marked all Beta plugins and for the fps project that was working in HTML5 I documented whether or not the plugin was enabled or not. Then I disabled plugins in my archvis project ONE at a time and then exported to HTML and tested in a web page. It was the 7th beta plugin that I had to disable before the archvis project would work in HTML5.
The name of the plugin that after disabling allowed my archvis project to run in HTML5 was “MDL/AxF Importer”
I sincerely hope this information is of benefit to someone! And I greatly appreciate everyone’s input and suggestions!
