The
following glossary includes a detailed list of the most common error codes
you may encounter and an explanation of each. Connection
Errors Invalid URL Invalid URL simply
means that the format of the URL was invalid. The format should be in one of the
following forms: http://www.someurl.com http://www.someurl.com/ http://www.someurl.com/page.jsp
http://www.someurl.com/page.jsp?QueryString No Response
From Web Server No response from Web server occurs when: The Web server's
IP address was found. A connection was established to the host computer running
the Web server. A request was made to the Web server using the URL at which time
there was no response from the Web server. Host Not
Found Host not found occurs when the Web server's host computer could not
be found using either its IP address or its host/domain name (Fully Qualified
Domain Name). Time Out A time out occurs when
a connection is established with a Web server, but the elapsed time to get the
URL content has exceeded a predetermined set time. The default time out is set
to 90 seconds. Connection Refused Connection
refused occurs when the Web server's host computer is found, but the host computer
refuses to establish a connection. Unexpected Error
Unexpected error occurs when a connection cannot be made to the computer
hosting the Web server and the error cannot be determined. This error is normally
due to improperly configured firewalls and/or routers performing packet filtering.
top ^ Web Server Status Codes/Messages
The Status-Code element is a 3-digit integer result code of the attempt
to understand and satisfy the request. These codes are defined below. The Status
Message is intended to give a short textual description of the Status-Code.
1xx: Informational - Request received,
continuing process 2xx: Success -
The action was successfully received, understood, and accepted 3xx:
Redirection - Further action must be taken in order to complete the
request 4xx: Client Error
- The request contains bad syntax or cannot be fulfilled 5xx:
Server Error - The server failed to fulfil an apparently valid request
top ^ 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.
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.
100 Continue The client may 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. 101 Switching Protocols The server understands and is willing to comply
with the client's request, via the Upgrade message header field (section 14.41),
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 only be switched 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 may be advantageous when delivering resources
that use such features. Successful 2xx All
response codes that start with 2xx indicates that the request was successfully
received, understood, and accepted.
200 OK The request has succeeded. 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 URL for the resource given by a Location
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. 202 Accepted The request has been
accepted for processing, but the processing has not been completed. The request
MAY or MAY NOT eventually be acted upon, as it MAY 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 noncommittal.
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. 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 MAY 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). 204 No Content The server has fulfilled the request but there is
no new information to send back. 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. The response MAY include new
metainformation in the form of entity-headers, which SHOULD apply to the document
currently in the user agent's active view. 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. 206 Partial Content The server has fulfilled
the partial GET request for the resource. The request must have included a Range
header field (section 14.36) indicating the desired range. The response MUST include
either a Content-Range header field (section 14.17) indicating the range included
with this response, or a multipart/byte-ranges Content-Type including Content-Range
fields for each part. If multipart/byte-ranges is not used, the Content-Length
header field in the response MUST match the actual number of Octets transmitted
in the message-body. A cache that does not support the Range and Content-Range
headers MUST NOT cache 206 (Partial) responses. Redirection
3xx This class of status code indicates that further action needs to be
taken by the user agent in order to fulfil 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 user agent SHOULD NOT
automatically redirect a request more than 5 times, since such redirection's usually
indicate an infinite loop. 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 URL 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.
301 Moved Permanently The requested resource has been assigned a new permanent
URI and any future references to this resource SHOULD be done using one of the
returned URIs. Clients with link editing capabilities SHOULD 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.
If the new URI is a location, its URL 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. 302 Moved Temporarily 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. If the new
URI is a location, its URL 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:
When automatically redirecting a POST request after receiving a 302 status code,
some existing HTTP/1.0 user agents will erroneously change it into a GET request.
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 is not cacheable, but the response to the
second (redirected) request MAY be cacheable. If the new URI is a location, its
URL 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). 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 response MUST NOT
contain a message-body. The response MUST include the following header fields:
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
conditional GET used a strong cache validation, the response SHOULD NOT include
other entity-headers. Otherwise (i.e., the conditional GET used a weak validation),
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. The 304 response MUST NOT include a message-body,
and thus is always terminated by the first empty line after the header fields.
305 Use Proxy The requested resource MUST be accessed through the proxy given
by the Location field. The Location field gives the URL of the proxy. The recipient
is expected to repeat the request via the proxy. 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.
Note: 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. 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. 401 Unauthorised
The request requires user authentication. The response MUST include a WWW-Authenticate
header field containing a challenge applicable to the requested resource. The
client MAY repeat the request with a suitable Authorisation header field. If the
request already included Authorisation credentials, then the 401 response indicates
that authorisation 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 MAY include relevant
diagnostic information. 402 Payment Required This code is reserved for future
use. 403 Forbidden The server understood the request, but is refusing to fulfil
it. Authorisation 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.
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. 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. If the server does
not wish to make this information available to the client, the status code 403
(Forbidden) can be used instead. 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. 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. 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. 407 Proxy Authentication Required This code is
similar to 401 (Unauthorised), but indicates that the client MUST first authenticate
itself with the proxy. The proxy MUST return a Proxy-Authenticate header field
containing a challenge applicable to the proxy for the requested resource. The
client MAY repeat the request with a suitable Proxy-authorisation header field.
408 Request Time-out 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. 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 recognise 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
may not be possible and is not required. Conflicts are most likely to occur in
response to a PUT request. If versioning is being used and the entity being PUT
includes changes to a resource which conflict with those made by an earlier (third-party)
request, the server MAY use the 409 response to indicate that it can't complete
the request. In this case, the response entity SHOULD contain a list of the differences
between the two versions in a format defined by the response Content-Type. 410
Gone The requested resource is no longer available at the server and no forwarding
address is known. This condition SHOULD 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. 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.
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. 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 URL "black hole" of redirection (e.g., a redirected URL 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. 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.
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. 500 Internal Server Error The server encountered
an unexpected condition, which prevented it from fulfilling the request. 501 Not
Implemented The server does not support the functionality required to fulfil the
request. This is the appropriate response when the server does not recognise 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 fulfil 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, 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. 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 server is
indicating that it is unable or unwilling to complete the request using the same
major version as the client 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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