unreal sample project not running for HTML5


When trying to run unreal engine vehicle sample project for HTML5 in browser following error is popping up:

Fatal error: [File:D:\Build++UE4+Release-4.15+Compile\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp] [Line: 439]
Non-agnostic games on cooked platforms require a uproject file be specified.

Though this runs absolutely fine when packed for windows standalone.
Any help is greatly appreciated! Thank you.