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Help for HTTP error 505: “HTTP Version not supported”

This HTTP error occurs when a web server receives a request that asks to use a version of HTTP that the server does not support. Most web servers and browsers use HTTP version 1.1, though some use v1.0 and few use v0.9.

Outline: Symptoms   Cause   Extra information


Internet Explorer may report this as “The website is unable to display the webpage

Microsoft Windows Update reports HTTP 505 errors with error code 0x80244024 (hexadecimal 80244024).

Apache web servers report this as follows (text in blue may vary):

HTTP Version Not Supported

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Further diagnosis

The official definition of this error states that “The response SHOULD contain an entity describing why that version is not supported and what other protocols are supported by that server.” [RFC 2616], so carefully search the response for clues as to what to do. (You may have to disable Internet Explorer friendly HTTP error messages in order to see what the server returned.)


To determine which HTTP version the server is using, view the HTTP headers that are sent when you request an object from the server, and pay attention to the first line of the response from the server.

Official description

What you can do about it

Extra information

HTTP versions are identified by two integers, which identify the major and minor version, separated by a period, e.g. “0.9” or “1.1”.

HTTP versions are defined in the following documents:

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