I'm running a flask web app and i getting an error like this: get (some js source) net::err_invalid_http_response

But the problem is when I trying to get the page the scripts that not working are different, sometimes all the scripts are working.

When I putting the scripts on the head of html it's loading better but still not all the scripts are working, but when I slowing down the internet to 3G in devtools all the scripts are running

I don't know what to do with it and I couldn't find nothing about it.

Im am using the standard script markup in html: <script src="some/js"></script>

Thanks in advance!