HTTP 505 HTTP Version Not Supported

What Does HTTP 505 Mean?

HTTP 505 HTTP Version Not Supported indicates that the server does not support the HTTP protocol version used in the request. The server is unable or unwilling to process the request with the given protocol version.

HTTP 505 is rare in practice since most servers support HTTP/1.0, HTTP/1.1, and HTTP/2. It might occur when a client uses an obsolete or experimental HTTP version that the server doesn't support.

If you encounter a 505 error, check that your client is using a standard HTTP version. Most modern browsers and HTTP libraries automatically negotiate the highest supported version, making 505 errors extremely uncommon in normal web browsing.

Common Causes of 505 HTTP Version Not Supported

The server doesn't support the HTTP version in the request. Common causes: using an obsolete HTTP version, experimental protocol features, and misconfigured client HTTP settings.

This is extremely rare with modern browsers and servers.

How to Fix 505 HTTP Version Not Supported

Update your HTTP client to use a supported HTTP version. Most servers support HTTP/1.1 and HTTP/2. If the server only supports HTTP/1.0, configure your client accordingly.

This error is extremely rare with modern software — if encountered, it likely indicates a severely outdated or misconfigured client or server.

Related Status Codes

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