[Error Fixed] 505 Error: HTTP Version Is Not Supported

The HTTP error 505: HTTP Version Not Supported response status code indicates that the server does not support the HTTP version used in the request.

Let us discuss what causes this error and possible solutions

What Is The Cause Of This Error?

When a client communicates with a web server, a series of steps are taken. For example, a short list of them is as follows:

  • Get an IP address from the site’s IP address (the URL without the leading ‘http://’). Domain name servers provide this lookup (conversion of IP address to IP name) (DNSs).
  • Connect to that IP address via an IP socket.
  • Send an HTTP data stream over that socket.
  • In response, receive an HTTP data stream from the Web server. The HTTP protocol determines the values of the status codes in this data stream. This data stream should be parsed for status codes and other useful information.

When the web server does not support or refuses to support the HTTP protocol version specified by the client in the HTTP request data stream sent to the server, the 505 error stage is returned.

How To Fix This Error?

The HTTP protocol is divided into major and minor versions. Typically, this error indicates that the server is unable or unwilling to complete the request using the same major version as the client. The server will generate a representation for the 505 response that explains why that version is not supported and what other protocols the server supports.

To test this, connect to a couple of major websites via telnet and run the following command:


You may receive the following response:

HTTP/1.1 505 Not Supported HTTP Version

Cloudflare is the server.

Date: Tuesday, August 17, 2020, 15:23:35 GMT

Text/HTML is the content-type.

Content length: 201 words

close connection

  • If you see this error in your browser, try a newer version or switch to a modern browser to see if it disappears.
  • Additionally, if you continue to see this error in your Web browser, upgrade your original Web server software to support the major version of the HTTP protocol that you require.

Also read:- [Fixed] Error Code 20 The Proxy Failed To Connect To The Web Server Due To Tcp Connection Timeout.


The error occurs when the HTTP version used in this particular request is not supported by the server. We saw how you can easily solve this error on your own. Try this fix for yourself and let us know the result.

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