Firefox HTML deployment error


I deployed on Firefox, but I get this error immediately.

Expression ((ReadPtr + Size + 2*sizeof(uint32)) <= RecieveBuffer.Num()) failed in D:\Build\++UE4+Release-4.14+Compile\Sync\Engine\Source\Runtime\NetworkFile\Private\HTTPTransport.cpp:181!
Check console for details.


Expression '(ReadPtr + Size + 2*sizeof(uint32)) <= RecieveBuffer.Num()' failed in D:\Build\++UE4+Release-4.14+Compile\Sync\Engine\Source\Runtime\NetworkFile\Private\HTTPTransport.cpp:181!
    at EPq (6454c3ef-e531-41da-b6d6-d334ab3eb160:93:1)
    at myh (6454c3ef-e531-41da-b6d6-d334ab3eb160:34:1)
    at bmC (6454c3ef-e531-41da-b6d6-d334ab3eb160:110:1)
    at KZb (6454c3ef-e531-41da-b6d6-d334ab3eb160:62:1)
    at __a (6454c3ef-e531-41da-b6d6-d334ab3eb160:29:1)
    at KWq (6454c3ef-e531-41da-b6d6-d334ab3eb160:93:1)
    at jHc (6454c3ef-e531-41da-b6d6-d334ab3eb160:59:1)
    at Rs (6454c3ef-e531-41da-b6d6-d334ab3eb160:103:1)
    at uK (6454c3ef-e531-41da-b6d6-d334ab3eb160:61:1)
    at bgj (6454c3ef-e531-41da-b6d6-d334ab3eb160:73:1)
    at A5i (6454c3ef-e531-41da-b6d6-d334ab3eb160:73:1)
    at asm._main (60667844-524c-4b97-b89d-7396c3183aa3:132:34553)
    at callMain (60667844-524c-4b97-b89d-7396c3183aa3:132:180716)
    at doRun (60667844-524c-4b97-b89d-7396c3183aa3:132:181635)
    at run/< (60667844-524c-4b97-b89d-7396c3183aa3:132:181803)  60667844-524c-4b97-b89d-7396c3183aa3:1:326595
uncaught exception: ASM_CONSTS<@blob:http://localhost:53501/60667844-524c-4b97-b89d-7396c3183aa3:1:28354

EDIT: basically the same thing on Chrome.


  • Have you tested this in 4.14.1?
  • Which version of FireFox are you on?
  • Have you tested this in Chrome?

Looking forward to hearing back from you, thanks!

I’ve just installed v4.14.1, but unfortunately it did not remedy the situation. I’m testing on Firefox v50.0.2 & Chrome v54.0.2840.99 m (64-bit).

I also get this message in the UE4 launch log (on Chrome):

HTML5LaunchHelper: [1211/] Could not find exported function RelaunchChromeBrowserWithNewCommandLineIfNeeded

Is this happening on any project that you launch for HTML5?

I am using FireFox version: 49.0.2 and Chrome version: 54.0.2840.99 m (64-bit). I also checked in FireFox version 50.0.2 and did not have any trouble. I am using a blank project.

Okay, so I’ve tested it on three projects so far: Basic C++ Code, Blank Blueprint & C++ FPS Template. It does work if I just press the “Launch” button, but if I launch it from the project launcher the same issue emerges yet again. This happened on the fresh C++ FPS Template & I didn’t change the project/launch config in any way, I just launched it from the project launcher straight away.

[Here’s the full log of that][1]

118477-projectlauncher.log (34.2 KB)


I have submitted [UE-39714][1] for this issue. Let me know if you have any further questions.


Unreal Engine Issues and Bug Tracker (UE-39714)

this bug is fixed for 4.15 – tracked in (UE-38281 & UE-22166)

the change list contains a number of fixes that wouldn’t be easy to just list them here to get your 4.14.1 running.

a few things to get the fix:

  • it will be up in the github repository sometime next week (the merge to main is happening right now)
  • you can wait for the official 4.15 release (which i think is in feb)
  • or, do not use the “cook on the fly” – but use “by the book” cook option (this will be the same as using the “launch” button)

Thanks a lot, Nick. I’ll just use the “by the book” cooking then.

Thanks kindly for your help, .