Each Status-Code is described below, including a description of which method(s) it can follow and any metainformation required in the response.
10.1 Informational
1xx
This class of status code indicates a provisional response,
consisting only of the Status-Line and optional headers, and is terminated by
an empty line. There are no required headers for this class of status code.
Since HTTP/1.0 did not define any 1xx status codes, servers MUST NOT send a 1xx
response to an HTTP/1.0 client except under experimental conditions.
A client MUST be prepared to accept one or more 1xx status
responses prior to a regular response, even if the client does not expect a 100
(Continue) status message. Unexpected 1xx status responses MAY be ignored by a
user agent.
Proxies MUST forward 1xx responses, unless the connection between
the proxy and its client has been closed, or unless the proxy itself requested
the generation of the 1xx response. (For example, if a
proxy adds a "Expect: 100-continue" field when it
forwards a request, then it need not forward the corresponding 100 (Continue)
response(s).)
10.1.1 100 Continue
The client SHOULD continue with its request. This interim response
is used to inform the client that the initial part of the request has been
received and has not yet been rejected by the server. The client SHOULD
continue by sending the remainder of the request or, if the request has already
been completed, ignore this response. The server MUST send a final response
after the request has been completed. See section 8.2.3 for detailed discussion of the use and
handling of this status code.
10.1.2 101 Switching Protocols
The server understands and is willing to comply with the client's
request, via the Upgrade message header field (section 14.42), for a change in
the application protocol being used on this connection. The server will switch
protocols to those defined by the response's Upgrade header field immediately
after the empty line which terminates the 101 response.
The protocol SHOULD be switched only when it is advantageous to do
so. For example, switching to a newer version of HTTP is advantageous over
older versions, and switching to a real-time, synchronous protocol might be
advantageous when delivering resources that use such features.
10.2 Successful 2xx
This class of status code indicates that the client's request was
successfully received, understood, and accepted.
10.2.1 200 OK
The request has succeeded. The information returned with the
response is dependent on the method used in the request, for example:
GET an entity corresponding to the requested resource is sent in
the response;
HEAD the entity-header fields corresponding to the requested
resource are sent in the response without any message-body;
POST an entity describing or containing the result of the action;
TRACE an entity containing the request message as received by the
end server.
10.2.2 201 Created
The request has been fulfilled and resulted in a new resource
being created. The newly created resource can be referenced by the URI(s)
returned in the entity of the response, with the most specific URI for the
resource given by a Location header field. The response SHOULD include an
entity containing a list of resource characteristics and location(s) from which
the user or user agent can choose the one most appropriate. The entity format
is specified by the media type given in the Content-Type header field. The
origin server MUST create the resource before returning the 201 status code. If
the action cannot be carried out immediately, the server SHOULD respond with
202 (Accepted) response instead.
A 201 response MAY contain an ETag response header field
indicating the current value of the entity tag for the requested variant just
created, see section 14.19.
10.2.3 202 Accepted
The request has been accepted for processing, but the processing
has not been completed. The request might or might not eventually be acted
upon, as it might be disallowed when processing actually takes place. There is
no facility for re-sending a status code from an asynchronous operation such as
this.
The 202 response is intentionally non-committal. Its purpose is to
allow a server to accept a request for some other process (perhaps a
batch-oriented process that is only run once per day) without requiring that
the user agent's connection to the server persist until the process is
completed. The entity returned with this response SHOULD include an indication
of the request's current status and either a pointer to a status monitor or
some estimate of when the user can expect the request to be fulfilled.
10.2.4 203 Non-Authoritative Information
The returned metainformation in the entity-header is not the
definitive set as available from the origin server, but is gathered from a
local or a third-party copy. The set presented MAY be a subset or superset of
the original version. For example, including local annotation information about
the resource might result in a superset of the metainformation known by the
origin server. Use of this response code is not required and is only
appropriate when the response would otherwise be 200 (OK).
10.2.5 204 No Content
The server has fulfilled the request but does not need to return
an entity-body, and might want to return updated metainformation. The response
MAY include new or updated metainformation in the form of entity-headers, which
if present SHOULD be associated with the requested variant.
If the client is a user agent, it SHOULD NOT change its document
view from that which caused the request to be sent. This response is primarily
intended to allow input for actions to take place without causing a change to
the user agent's active document view, although any new or updated
metainformation SHOULD be applied to the document currently in the user agent's
active view.
The 204 response MUST NOT include a message-body, and thus is
always terminated by the first empty line after the header fields.
10.2.6 205 Reset Content
The server has fulfilled the request and the user agent SHOULD
reset the document view which caused the request to be sent. This response is
primarily intended to allow input for actions to take place via user input,
followed by a clearing of the form in which the input is given so that the user
can easily initiate another input action. The response MUST NOT include an
entity.
10.2.7 206 Partial Content
The server has fulfilled the partial GET request for the resource.
The request MUST have included a Range header field (section 14.35) indicating
the desired range, and MAY have included an If-Range header field
(section 14.27) to make the request conditional.
The response MUST include the following header fields:
- Either a
Content-Range header field (section 14.16) indicating
the range included
with this response, or a multipart/byteranges
Content-Type
including Content-Range fields for each part. If a
Content-Length
header field is present in the response, its
value MUST match the
actual number of OCTETs transmitted in the
message-body.
- Date
- ETag and/or
Content-Location, if the header would have been sent
in a 200 response to
the same request
- Expires,
Cache-Control, and/or Vary, if the field-value might
differ from that
sent in any previous response for the same
variant
If the 206 response is the result of an If-Range request that used
a strong cache validator (see section 13.3.3), the response SHOULD NOT include
other entity-headers. If the response is the result of an If-Range request that
used a weak validator, the response MUST NOT include other entity-headers; this
prevents inconsistencies between cached entity-bodies and updated headers.
Otherwise, the response MUST include all of the entity-headers that would have
been returned with a 200 (OK) response to the same request.
A cache MUST NOT combine a 206 response with other previously
cached content if the ETag or Last-Modified headers do not match exactly,
see 13.5.4.
A cache that does not support the Range and Content-Range headers
MUST NOT cache 206 (Partial) responses.
10.3 Redirection 3xx
This class of status code indicates that further action needs to
be taken by the user agent in order to fulfill the request. The action required
MAY be carried out by the user agent without interaction with the user if and
only if the method used in the second request is GET or HEAD. A client SHOULD
detect infinite redirection loops, since such loops generate network traffic
for each redirection.
Note: previous
versions of this specification recommended a
maximum of five
redirections. Content developers should be aware
that there might be clients that implement
such a fixed
limitation.
10.3.1 300 Multiple Choices
The requested resource corresponds to any one of a set of
representations, each with its own specific location, and agent- driven
negotiation information (section 12) is being provided so that the user (or
user agent) can select a preferred representation and redirect its request to
that location.
Unless it was a HEAD request, the response SHOULD include an
entity containing a list of resource characteristics and location(s) from which
the user or user agent can choose the one most appropriate. The entity format
is specified by the media type given in the Content- Type header field.
Depending upon the format and the capabilities of
the user agent, selection of the most appropriate choice MAY be
performed automatically. However, this specification does not define any
standard for such automatic selection.
If the server has a preferred choice of representation, it SHOULD
include the specific URI for that representation in the Location field; user
agents MAY use the Location field value for automatic redirection. This
response is cacheable unless indicated otherwise.
10.3.2 301 Moved Permanently
The requested resource has been assigned a new permanent URI and
any future references to this resource SHOULD use one of the returned URIs.
Clients with link editing capabilities ought to automatically re-link
references to the Request-URI to one or more of the new references returned by
the server, where possible. This response is cacheable unless indicated
otherwise.
The new permanent URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the response SHOULD
contain a short hypertext note with a hyperlink to the new URI(s).
If the 301 status code is received in response to a request other
than GET or HEAD, the user agent MUST NOT automatically redirect the request
unless it can be confirmed by the user, since this might change the conditions
under which the request was issued.
Note: When automatically
redirecting a POST request after
receiving a 301 status
code, some existing HTTP/1.0 user agents
will erroneously
change it into a GET request.
10.3.3 302 Found
The requested resource resides temporarily under a different URI.
Since the redirection might be altered on occasion, the client SHOULD continue
to use the Request-URI for future requests. This response is only cacheable if
indicated by a Cache-Control or Expires header field.
The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the response SHOULD
contain a short hypertext note with a hyperlink to the new URI(s).
If the 302 status code is received in response to a request other
than GET or HEAD, the user agent MUST NOT automatically redirect the request
unless it can be confirmed by the user, since this might change the conditions
under which the request was issued.
Note: RFC 1945 and RFC
2068 specify that the client is not allowed
to change the method
on the redirected request. However, most
existing user agent
implementations treat 302 as if it were a 303
response, performing a
GET on the Location field-value regardless
of the original
request method. The status codes 303 and 307 have
been added for servers
that wish to make unambiguously clear which
kind of reaction is
expected of the client.
10.3.4 303 See Other
The response to the request can be found under a different URI and
SHOULD be retrieved using a GET method on that resource. This method exists
primarily to allow the output of a POST-activated script to redirect the user
agent to a selected resource. The new URI is not a substitute reference for the
originally requested resource. The 303 response MUST NOT be cached, but the
response to the second (redirected) request might be cacheable.
The different URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the response SHOULD
contain a short hypertext note with a hyperlink to the new URI(s).
Note: Many
pre-HTTP/1.1 user agents do not understand the 303
status. When
interoperability with such clients is a concern, the
302 status code may be
used instead, since most user agents react
to a 302 response as
described here for 303.
10.3.5 304 Not Modified
If the client has performed a conditional GET request and access
is allowed, but the document has not been modified, the server SHOULD respond
with this status code. The 304 response MUST NOT contain a message-body, and
thus is always terminated by the first empty line after the header fields.
The response MUST include the following header fields:
- Date, unless its
omission is required by section 14.18.1
If a clockless origin server obeys these rules, and proxies and
clients add their own Date to any response received without one (as already
specified by [RFC 2068], section 14.19), caches will operate correctly.
- ETag and/or
Content-Location, if the header would have been sent
in a 200 response to
the same request
- Expires,
Cache-Control, and/or Vary, if the field-value might
differ from that
sent in any previous response for the same
variant
If the conditional GET used a strong cache validator (see section
13.3.3), the response SHOULD NOT include other entity-headers. Otherwise (i.e.,
the conditional GET used a weak validator), the response MUST NOT include other
entity-headers; this prevents inconsistencies between cached entity-bodies and
updated headers.
If a 304 response indicates an entity not currently cached, then
the cache MUST disregard the response and repeat the request without the
conditional.
If a cache uses a received 304 response to update a cache entry,
the cache MUST update the entry to reflect any new field values given in the
response.
10.3.6 305 Use Proxy
The requested resource MUST be accessed through the proxy given by
the Location field. The Location field gives the URI of the proxy. The
recipient is expected to repeat this single request via the proxy. 305
responses MUST only be generated by origin servers.
Note: RFC 2068 was not
clear that 305 was intended to redirect a
single request, and to
be generated by origin servers only. Not
observing these
limitations has significant security consequences.
10.3.7 306 (Unused)
The 306 status code was used in a previous version of the
specification, is no longer used, and the code is reserved.
10.3.8 307 Temporary Redirect
The requested resource resides temporarily under a different URI.
Since the redirection MAY be altered on occasion, the client SHOULD continue to
use the Request-URI for future requests. This response is only cacheable if
indicated by a Cache-Control or Expires header field.
The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the response SHOULD
contain a short hypertext note with a hyperlink to the new URI(s) , since many
pre-HTTP/1.1 user agents do not understand the 307 status. Therefore, the note
SHOULD contain the information necessary for a user to repeat the original
request on the new URI.
If the 307 status code is received in response to a request other
than GET or HEAD, the user agent MUST NOT automatically redirect the request
unless it can be confirmed by the user, since this might change the conditions
under which the request was issued.
10.4 Client Error 4xx
The 4xx class of status code is intended for cases in which the
client seems to have erred. Except when responding to a HEAD request, the server
SHOULD include an entity containing an explanation of the error situation, and
whether it is a temporary or permanent condition. These status codes are
applicable to any request method. User agents SHOULD display any included
entity to the user.
If the client is sending data, a server implementation using TCP
SHOULD be careful to ensure that the client acknowledges receipt of the
packet(s) containing the response, before the server closes the input
connection. If the client continues sending data to the server after the close,
the server's TCP stack will send a reset packet to the client, which may erase
the client's unacknowledged input buffers before they can be read and
interpreted by the HTTP application.
10.4.1 400 Bad Request
The request could not be understood by the server due to malformed
syntax. The client SHOULD NOT repeat the request without modifications.
10.4.2 401 Unauthorized
The request requires user authentication. The response MUST
include a WWW-Authenticate header field (section 14.47) containing a challenge
applicable to the requested resource. The client MAY repeat the request with a
suitable Authorization header field (section 14.8). If the request already included
Authorization credentials, then the 401 response indicates that authorization
has been refused for those credentials. If the 401 response contains the same
challenge as the prior response, and the user agent has already attempted
authentication at least once, then the user SHOULD be presented the entity that
was given in the response, since that entity might include relevant diagnostic
information. HTTP access authentication is explained in "HTTP
Authentication: Basic and Digest Access Authentication" [43].
10.4.3 402 Payment Required
This code is reserved for future use.
10.4.4 403 Forbidden
The server understood the request, but is refusing to fulfill it.
Authorization will not help and the request SHOULD NOT be repeated. If the
request method was not HEAD and the server wishes to make public why the
request has not been fulfilled, it SHOULD describe the reason for the refusal
in the entity. If the server does not wish to make this information available
to the client, the status code 404 (Not Found) can be used instead.
10.4.5 404 Not Found
The server has not found anything matching the Request-URI. No
indication is given of whether the condition is temporary or permanent. The 410
(Gone) status code SHOULD be used if the server knows, through some internally
configurable mechanism, that an old resource is permanently unavailable and has
no forwarding address. 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.
10.4.6 405 Method Not Allowed
The method specified in the Request-Line is not allowed for the
resource identified by the Request-URI. The response MUST include an Allow
header containing a list of valid methods for the requested resource.
10.4.7 406 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.
Unless it was a HEAD request, the response SHOULD include an
entity containing a list of available entity characteristics and location(s)
from which the user or user agent can choose the one most appropriate. The
entity format is specified by the media type given in the Content-Type header
field. Depending upon the format and the capabilities of the user agent,
selection of the most appropriate choice MAY be performed automatically. However,
this specification does not define any standard for such automatic selection.
Note: HTTP/1.1 servers
are allowed to return responses which are
not acceptable
according to the accept headers sent in the
request. In some
cases, this may even be preferable to sending a
406 response. User
agents are encouraged to inspect the headers of
an incoming response
to determine if it is acceptable.
If the response could be unacceptable, a user agent SHOULD
temporarily stop receipt of more data and query the user for a decision on
further actions.
10.4.8 407 Proxy Authentication Required
This code is similar to 401 (Unauthorized), but indicates that the
client must first authenticate itself 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. The client MAY repeat the request with a
suitable Proxy-Authorization header field (section 14.34). HTTP access authentication is explained
in "HTTP Authentication: Basic and Digest Access
Authentication" [43].
10.4.9 408 Request Timeout
The client did not produce a request within the time that the
server was prepared to wait. The client MAY repeat the request without
modifications at any later time.
10.4.10 409 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. The response body SHOULD include enough
information for the user to recognize the source of the conflict.
Ideally, the response entity would include enough information for the user or
user agent to fix the problem; however, that might not be possible and is not
required.
Conflicts are most likely to occur in response to a PUT request.
For example, if versioning were being used and the entity being PUT included
changes to a resource which conflict with those made by an earlier
(third-party) request, the server might use the 409 response to indicate that
it can't complete the request. In this case, the response entity would likely
contain a list of the differences between the two versions in a format defined
by the response Content-Type.
10.4.11 410 Gone
The requested resource is no longer available at the server and no
forwarding address is known. This condition is expected to be considered
permanent. Clients with link editing capabilities SHOULD delete references to
the Request-URI after user approval. If the server does not know, or has no
facility to determine, whether or not the condition is permanent, the status
code 404 (Not Found) SHOULD be used instead. This response is cacheable unless
indicated otherwise.
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 desire that remote links to that
resource be removed. Such an event is common for limited-time, promotional
services and for resources belonging to individuals no longer working at the
server's site. It is not necessary to mark all permanently unavailable
resources as "gone" or to keep the mark for any length of time --
that is left to the discretion of the server owner.
10.4.12 411 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.
10.4.13 412 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.
10.4.14 413 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.
If the condition is temporary, the server SHOULD include a Retry-
After header field to indicate that it is temporary and after what time the
client MAY try again.
10.4.15 414 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. This rare
condition is only likely to occur when a client has improperly converted a POST
request to a GET request with long query information, when the client has
descended into a URI "black hole" of redirection (e.g., a redirected
URI prefix that points to a suffix of itself), or when the server is under
attack by a client attempting to exploit security holes present in some servers
using fixed-length buffers for reading or manipulating the Request-URI.
10.4.16 415 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.
10.4.17 416 Requested Range Not Satisfiable
A server SHOULD return a response with this status code if a
request included a Range request-header field (section 14.35), and none of the
range-specifier values in this field overlap the current extent of the selected
resource, and the request did not include an If-Range request-header field.
(For byte-ranges, this means that the first- byte-pos of all of the
byte-range-spec values were greater than the current length of the selected
resource.)
When this status code is returned for a byte-range request, the
response SHOULD include a Content-Range entity-header field specifying the
current length of the selected resource (see section14.16). This response MUST NOT use the
multipart/byteranges content- type.
10.4.18 417 Expectation Failed
The expectation given in an Expect request-header field (see
section 14.20) could not be met by this server, or, if the server is a proxy,
the server has unambiguous evidence that the request could not be met by the
next-hop server.
10.5 Server Error 5xx
Response status codes beginning with the digit "5"
indicate cases in which the server is aware that it has erred or is incapable
of performing the request. Except when responding to a HEAD request, the server
SHOULD include an entity containing an explanation of the error situation, and
whether it is a temporary or permanent condition. User agents SHOULD display
any included entity to the user. These response codes are applicable to any
request method.
10.5.1 500 Internal Server Error
The server encountered an unexpected condition which prevented it
from fulfilling the request.
10.5.2 501 Not Implemented
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.
10.5.3 502 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.
10.5.4 503 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, the client SHOULD handle the response as it would for a
500 response.
Note: The existence of
the 503 status code does not imply that a
server must use it
when becoming overloaded. Some servers may wish
to simply refuse the
connection.
10.5.5 504 Gateway Timeout
The server, while acting as a gateway or proxy, did not receive a
timely response from the upstream server specified by the URI (e.g. HTTP, FTP,
LDAP) or some other auxiliary server (e.g. DNS) it needed to access in
attempting to complete the request.
Note: Note to
implementors: some deployed proxies are known to
return 400 or 500 when
DNS lookups time out.
10.5.6 505 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 server is indicating
that it is unable or unwilling to complete the request using the same major
version as the client, as described in section 3.1, other than with this error 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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