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Sometimes when you try to visit a Web site, instead
of seeing what you expected, you see an error code.
Some of these codes may be familiar, but there are a
lot that you may have never seen. To give you a greater
understanding of these errors, here is a list of the
most popular codes.
As a rule of thumb, the first thing you should if
you get an error is make sure that you have typed in
the URL or page address correctly.
Bad request 400
The request could not be understood by the server due
to bad syntax. You should not repeat the request without
modifications.
Unauthorized 401
The creators of a Web page may want only certain people
have access to that page. You should only retry the
request if you know that you have authorization.
PaymentRequired 402
This message gives a specification of charging schemes
which are acceptable. You may retry the request with
a suitable ChargeTo header.
Forbidden 403
The request is for something forbidden. Authorization
will not help. This status code is commonly used when
the server does not wish to reveal exactly why the request
has been refused, or when no other response is applicable.
(The file needs to be set with "read permissions" for
all users.)
Not found 404
The server has not found anything matching what you
requested. Make sure that the Web address (URL) that
you typed in exactly matches the address you were given.
Check that the capitalization matches, spelling, and
punctuation, like dots (.) and slashes (/),
are correctly placed. Be sure you are using the forward
slash (/) and not the backward slash (\).
405 Method Not Allowed
The method specified in the Request-Line is not allowed
for the resource identified by the request. The response
must include an Allow header containing a list of valid
methods for the requested resource.
406 Not Acceptable
The resource identified by the request is only capable
of generating response entities which have content characteristics
not acceptable according to the accept headers sent
in the request.
407 Proxy Authentication Required
This code is similar to 401 (Unauthorized), but indicates
that you must first authenticate yourself with the proxy.
The proxy must return a Proxy-Authenticate header field
(section 14.33) containing a challenge applicable to
the proxy for the requested resource. You may repeat
the request with a suitable Proxy-Authorization header
field (section 14.34). HTTP access authentication is
explained in section 11.
408 Request Timeout
The client did not produce a request within the time
that the server was prepared to wait. You may repeat
the request without modifications at any later time.
409 Conflict
The request could not be completed due to a conflict
with the current state of the resource. This code is
only allowed in situations where it is expected that
the user might be able to resolve the conflict and resubmit
the request.
410 Gone
The 410 response is primarily intended to assist the
task of web maintenance by notifying the recipient that
the resource is intentionally unavailable and that the
server owners want remote links to that resource be
removed.
411 Length Required
The server refuses to accept the request without a defined
Content- Length. The client may repeat the request if
it adds a valid Content-Length header field containing
the length of the message-body in the request message.
412 Precondition Failed
The precondition given in one or more of the request-header
fields evaluated to false when it was tested on the
server. This response code allows the client to place
preconditions on the current resource metainformation
(header field data) and thus prevent the requested method
from being applied to a resource other than the one
intended.
413 Request Entity Too Large
The server is refusing to process a request because
the request entity is larger than the server is willing
or able to process. The server may close the connection
to prevent the client from continuing the request.
414 Request-URI Too Long
The server is refusing to service the request because
the Request-URI is longer than the server is willing
to interpret.
415 Unsupported Media Type
The server is refusing to service the request because
the entity of the request is in a format not supported
by the requested resource for the requested method.
Internal Error 500
The server encountered an unexpected condition which
prevented it from fulfilling the request. Your request
could not be processed due to an internal server error.
Not implemented 501
The server does not support the functionality required
to fulfill the request. This is the appropriate response
when the server does not recognize the request method
and is not capable of supporting it for any resource.
502 Bad Gateway
The server, while acting as a gateway or proxy, received
an invalid response from the upstream server it accessed
in attempting to fulfill the request.
503 Service Unavailable
The server is currently unable to handle the request
due to a temporary overloading or maintenance of the
server. The implication is that this is a temporary
condition which will be alleviated after some delay.
If known, the length of the delay may be indicated in
a Retry-After header. If no Retry-After is given, you
should handle the response as it would for a 500 response.
504 Gateway Timeout
The server, while acting as a gateway or proxy, did
not receive a timely response from the upstream server
it accessed in attempting to complete the request.
505 HTTP Version Not Supported
The server does not support, or refuses to support,
the HTTP protocol version that was used in the request
message. The response should contain an entity describing
why that version is not supported and what other protocols
are supported by that server.
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