"Error: Parse Error: Expected HTTP/" when using dns

Application Performance DNS & Network
1

I have a simple http rest api, which works perfectly when using the ip address directly. I made a dns A record (unproxied) pointing my domain to the ip address, which a traceroute confirms works. However, when using the domain in the browser, an ERR_INVALID_HTTP_RESPONSE error was displayed. Doing the same request in postman showed the error was “Error: Parse Error: Expected HTTP/”. The site still works perfectly with the ip.
The site uses http, I was using http to connect, and encryption mode on Cloudflare was off.

Anyone have an idea why this is occurring?

2

That seems as if the request or response header was not properly sent.

Would you have a URL as example? If it is unproxied, it won’t be Cloudflare related, as Cloudflare won’t be involved in the request.

3

a test server where the issue occurs: {removed}

4

Yeah, it seems to be an issue with the HTTP response and you would need to check out your server code for that. As I mentioned, the record is unproxied, so that response comes straight from your server.

5

the weird thing is it works perfectly fine when using the ip

6

With the IP address, it seems to be the same response. But I am afraid, that’s something beyond the scope of the forum here.

7

hm, odd.
my server uses the builtin sun http server in java, com.sun.net.httpserver.HttpServer.
i dont modify any headers, except Content-Type, setting it to application/json. The method i use to initiate the response (sendResponseHeaders()) actually starts the response with "HTTP/1.1 "+rCode+Code.msg(rCode)+"\r\n", so i really cant explain to myself why it seems to be missing in postman and the browser

8

You really best debug your code, as you are currently not composing a proper response.

If you need any further assistance, I would recommend to check out StackOverflow or Reddit.