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HTTP error
505 HTTP Version Not Supported
The server does not support the HTTP version of the request.
What it means
The request used a version of the HTTP protocol that the server will not handle. It is rare with modern browsers and usually points to an old server, a custom client or a malformed request line.
Common causes
- A very old web server or proxy
- A custom client that sends a wrong version
- A malformed request line
- A misconfigured proxy between the client and the server
How to fix it
If you are a visitor
- Update your browser
- Try another browser or network
If you run the site
- Update the web server and proxies
- Check the HTTP versions that each layer of your stack supports
- Check the request line that your client sends
Catch it before your users do
You can check the status code of any address right now. To hear about 505 errors as they happen, an HTTP(S) monitor requests the page around the clock, compares the response with the status codes you expect and alerts you when it does not match.
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