HTML 5 On Mobile fails on Value_GL_MAX_COLOR_ATTACHMENTS >= MaxSimultaneousRenderTargets

Hi, My HTML 5 mobile build fails with unknown exceptions:

Expression ‘Value_GL_MAX_COLOR_ATTACHMENTS >= MaxSimultaneousRenderTargets || !FOpenGL::SupportsMultipleRenderTargets()’ failed in D:/Build/++UE4/Sync/Engine/Source/Runtime/OpenGLDrv/Private/OpenGLDevice.cpp:749!
at FOpenGLDynamicRHI::FOpenGLDynamicRHI() (14a99e4e:wasm-function[27397]:0xf59d23)
at FOpenGLDynamicRHIModule::CreateRHI(ERHIFeatureLevel::Type) (14a99e4e:wasm-function[27396]:0xf58e0b)
at RHIInit(bool) (14a99e4e:wasm-function[28318]:0xfe9010)
at FEngineLoop::PreInit(wchar_t const*) (14a99e4e:wasm-function[851]:0xe86f2)
at FEngineLoop::PreInit(int, wchar_t**, wchar_t const*) (14a99e4e:wasm-function[838]:0xe3066)
at HTML5_Init() (14a99e4e:wasm-function[837]:0xe2e59)W

If I attempt to load PC version on mobile browser, I also get a warning:

“Your browser or graphics card does not support the following WebGL extensions: WEBGL_compressed_texture_s3tc, EXT_texture_filter_anisotropic. This can impact UE4 graphics performance and quality.”