Help for HyperText Transfer Protocol (HTTP) errors
Web browsers, such as Internet Explorer and Firefox use HTTP to access objects (e.g. web pages and images) on web servers. Whenever the server responds to a browser, it returns a 3 digit numeric status code and a textual “reason phrase”. The status codes are standardized, whereas the reason phrases can vary between servers. The first digit indicates the class of the code (e.g. client or server error), and the remaining digits identify the particular status.
A complete list of official HTTP status codes and reasons described in RFCs such as [RFC 2616]
|4xx Client error||400||Bad Request|
|405||Method Not Allowed|
|5xx Server error||500||Internal Server Error|
|505||HTTP Version not supported|
Several products report HTTP errors with their own description:
You can view them with online tools such as web-sniffer.net
For information about
For a flow chart of how status codes are arrived at.
If you're curious about what weird and interesting stuff can appear in HTTP headers, see:
A. Wooster: “Fun With HTTP Headers”
1The reasons listed here are the official suggestions from [RFC 2616], others are listed in the page about the code.