HTML5 game wont start

Hello everyone! I’m having issues with getting the game to actually load onto Firefox Nightly. I followed the steps to open the HTML5Helper, then opened the .html file in Nightly… but I’m looking at this

and the helper doesnt seem to connect

however, my files for the HTML5 are…kinda big… would the size of the game matter??

Any help or direction would be stelar Dx

I have the same issue, HTML 5 has not worked for me since UE4.9 came out, I get same issue with UE4.10

Muchly agreed. Something is up with HTML5.


Looking that your project is upwards of 1gb you are more likely to see long loading times or errors for something that is supposed to be loaded into the browser to run.

You can try packaging only the maps you want by setting these in the package section of the Project Settings. This may help reduce the size to only the assets in your project map.

As for testing 4.9 and builds loading in HTML5. I just tested this without issue on 4.9 and 4.10.

I did not have Firefox previously installed so I downloaded the latest nightly build for Windows from here:

I then re-installed Emscripten from here:

Next I installed the latest Python 2.7.10 from here: Download Python |

Then when I loaded up 4.9 I was able to see my list of HTML5 64-bit compatible browsers listed to launch to. (Chrome and FireFox).

If you’re not seeing anything here, be sure to check the Project Settings > HTML5 SDK section. Make sure that you have your browser listed in the drop down rollout. If not, navigate to it’s file path from here and give it a name.

As for testing, if everything appears to work do the following:

  • Create a new project.
  • Set to Mobile
  • 2D/3D scalability
  • No Starter Content

Once the project loads up do the following:

  • Add a couple of the basic static meshes (sphere and cube) from the Modes panel in the upper left.
  • Save the map
  • Click the Toolbar Launch dropdown arrow.
  • Select your HTML5 browser and launch.
  • Wait for it to launch. This can take a few minutes to package it and get it up. And keep in mind that this is a small test project. Packaging takes a bit of time.

Give that a shot and let me know.