HTTP 505 HTTP Version Not Supported — What It Means & How to Fix It

The HTTP 505 HTTP Version Not Supported status code indicates the server does not support the HTTP protocol version used in the request. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: The server does not support or refuses to support the major HTTP version in the request.. The response should indicate which protocol versions the server supports.. This is rare in practice as most servers support HTTP/1.0, HTTP/1.1, and HTTP/2.. It may occur with very old clients or experimental protocol versions.. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: The client is using an HTTP version the server does not support.. A very old HTTP/1.0 client connecting to a server that only supports HTTP/1.1+.. Experimental or draft HTTP version being used.. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Check what HTTP version your client is using and switch to a supported version.. Update your HTTP client or browser to support modern HTTP versions.. Verify the server configuration supports the common HTTP versions.. Try forcing HTTP/1.1 if the server does not support HTTP/2.. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our HTTP Status Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.