HTML5 uncaught typeError: cannot read property 'toLowerCase' of null

Hi everyone

It’s my first time at packaging for HTML5 and I’ve read a lot of guides and answers around the web before posting here, like Html5, Building on Windows, guide1, etc…

When I package the project my Logs gives me no errors or warnings but as you can see here ( project website link)I get this error:

on my Web Host i loaded these files

https://forums.unrealengine.com/filedata/fetch?filedataid=123169&type=thumb

and I avoided to load these ones

https://forums.unrealengine.com/filedata/fetch?filedataid=123170&type=thumb

I’ve create a Blank Blueprints project with these settings : Mobile / Tablet Scalable 2D or 3D No Starter Content

PROJECT SETTINGS
Packaging Build Configuration: Shipping Client

Options checked
Full Rebuil
For Distribution
Use Pak File
Share Material Shader Code
Shared Material Native Libraries
Cook only map
Create compressed cooked packages
Include prerequisites installer

PLATFORMS -HTML5

Options checked
Compress file during shipping packaging

please help me to fix this problem. Thank you