Is it possible to disable HTTP/2 for the netty server engine? I have a legacy application and HTTP/2...

# ktor

[Tóth István Zoltán]

Is it possible to disable HTTP/2 for the netty server engine? I have a legacy application and HTTP/2 brings out a bug in Chrome (an XHR request is in pending status, it does not arrive to the server).

[James]

AFAIK it is the client that controls which http version to use

[Tóth István Zoltán]

That's the problem, Chrome wants HTTP/2 but then it does not work properly. In Firefox everything is OK. When I use the same Javascript with a non-Ktor HTTP/1.1 server, it works in Chrome as well.

[James]

What is the error you are receiving by XHR?

[Tóth István Zoltán]

There is no error, it is in "pending" forever.

[Tóth István Zoltán]

And the Ktor log for the requests above.

[James]

XHR Requests in browser are supposed to support HTTP/2 as far as I know, so it is weird it gets stuck at pending

[James]

Do you have a service worker that intercepts requests?

[Tóth István Zoltán]

No, it is a simple XMLHttpRequest, no workers. This is a quite old legacy application.

Thanks for the answers btw.

[James]

Are you able to share the code that calls the endpoint?

[Tóth István Zoltán]

This is what I have. xmlhttp is a new XMLHttpRequest.

this.send = function(url, body, handler) {
        try {
            responseHandler = handler;
            xmlhttp.open("post", url, true);
            for (var i = 0; i < headers.length; i++) {
                var header = headers[i];
                xmlhttp.setRequestHeader(header.name, header.value);
            }

            if (<http://hx.ie|hx.ie>)
                xmlhttp.setRequestHeader("If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT");

            xmlhttp.onreadystatechange = this.handleResponse;
            xmlhttp.send(body);
        } catch (err) {
            hx.doError("Message error", null, err);
        }
    }

[James]

Untitled.js

Untitled.js

[James]

I don't see anything instantly wrong with that.. Chances are there might be something blocking the thread.

[James]

This might also be a chrome issue, https://support.google.com/chrome/thread/49442697/xhr-requests-pending-for-a-long-time[…]-chrome-updates-when-not-recording-in-performance-tab?hl=en

[James]

Do you get the same issue in Chromium?

[Tóth István Zoltán]

Haven't tried to be honest. But, you've just gave me an idea, I'll try to add a small delay on the server side so the order of answers will be different.

[Tóth István Zoltán]

Hm, I've added an nxign proxy between Ktor and Chrome and now it works. Something is fishy in the Ktor-Netty-SSL-HTTP/2 setup.