It is unclear to me when you should and should not return a HTTP 412: Precondition Failed, error for a web service? I am thinking of using it when validating data. For example, if a client POST’s XML data and that data is missing a required data element, then responding with a 412 and a description of the error.
Does that align with the spirit of responding with an HTTP 412, or should something else be used (e.g. another http error code or web application exception)?
Elias Zamaria
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asked Mar 20, 2011 at 15:40
2
If you look at RFC 2616 you’ll see a number of request headers that can be used to apply conditions to a request:
If-Match
If-Modified-Since
If-None-Match
If-Range
If-Unmodified-Since
These headers contain ‘preconditions’, allowing the client to tell the server to only complete the request if certain conditions are met. For example, you use a PUT
request to update the state of a resource, but you only want the PUT
to be actioned if the resource has not been modified by someone else since your most recent GET
.
The response status code 412
(Precondition Failed) is typically used when these preconditions fail.
Your example sounds like an invalid request (i.e. the client has submitted data that is invalid because of missing values). A status code of 400
(Bad Request) is more appropriate here IMO.
answered Mar 20, 2011 at 15:57
joelittlejohnjoelittlejohn
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2
412 is reserved for cases where the request is conditional, and the condition isn’t met.
For your use case, 422 Unprocessable Entity is a good match.
answered Mar 20, 2011 at 16:47
Julian ReschkeJulian Reschke
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4
Your best bet would be to avoid 412. In practice most web services that I’ve used send a 400 code (Bad Request). A lot of frameworks have built-in support for 400 too and your clients will appreciate a more common error code. Often times, especially with REST interfaces, a simple «message» or «error» element is returned with a description.
answered Mar 20, 2011 at 15:46
Matt BishopMatt Bishop
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3
412 Предупреждение Ошибка
Протокол передачи гипертекста (HTTP) 412 Precondition Failed
client error response code указывает, что доступ к целевому ресурсу был запрещен. Это происходит с условными запросами к методам, отличным от GET
или HEAD
, когда условие, определенное заголовками If-Unmodified-Since
или If-None-Match
, не выполняется. В этом случае запрос, обычно загрузка или изменение ресурса, не может быть выполнен, и этот ответ об ошибке отправляется обратно.
Status
Examples
ETag: "33a64df551425fcc55e4d42a148795d9f25f89d4" ETag: W/"0815"
Предотвращение столкновений в воздухе
С помощью ETag
и If-Match
вы можете обнаруживать конфликты редактирования в воздухе.
Например, при редактировании MDN текущий контент вики хешируется и помещается в Etag
в ответе:
ETag: "33a64df551425fcc55e4d42a148795d9f25f89d4"
При сохранении изменений на вики-странице (данные публикации) запрос POST
будет содержать заголовок If-Match
, содержащий значения ETag
, по которым выполняется проверка актуальности .
If-Match: "33a64df551425fcc55e4d42a148795d9f25f89d4"
Если хэши не совпадают, это означает, что документ был отредактирован между ними, и Precondition Failed
ошибка 412
Precondition Failed .
Specifications
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox для Android | Opera Android | Safari на IOS | Samsung Internet | |
412 |
Yes |
12 |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
See also
304
If-Unmodified-Since
If-None-Match
428
HTTP
-
410 Gone
Код ответа ошибки клиента HyperText Transfer Protocol (HTTP)410 Gone указывает,что доступ к целевому ресурсу больше не доступен серверу происхождения и
-
411 Требуемая длина
Код ошибки ответа клиента HyperText Transfer Protocol (HTTP)411 Length Required указывает,что сервер отказывается принимать запрос без определенной Content-Length.
-
413 Слишком большая грузоподъемность
Код состояния ответа HTTP 413 Payload Too Large указывает на то,что объект запроса превышает пределы,определенные сервером;возможно закрытие соединения или возврат Retry-After
-
414 УРТ слишком длинный
Код состояния ответа HTTP 414 URI Too Long указывает на то,что запрос клиента длиннее,чем сервер готов интерпретировать.
From Wikipedia, the free encyclopedia
This is a list of Hypertext Transfer Protocol (HTTP) response status codes. Status codes are issued by a server in response to a client’s request made to the server. It includes codes from IETF Request for Comments (RFCs), other specifications, and some additional codes used in some common applications of the HTTP. The first digit of the status code specifies one of five standard classes of responses. The optional message phrases shown are typical, but any human-readable alternative may be provided, or none at all.
Unless otherwise stated, the status code is part of the HTTP standard (RFC 9110).
The Internet Assigned Numbers Authority (IANA) maintains the official registry of HTTP status codes.[1]
All HTTP response status codes are separated into five classes or categories. The first digit of the status code defines the class of response, while the last two digits do not have any classifying or categorization role. There are five classes defined by the standard:
- 1xx informational response – the request was received, continuing process
- 2xx successful – the request was successfully received, understood, and accepted
- 3xx redirection – further action needs to 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
1xx informational response
An informational response indicates that the request was received and understood. It is issued on a provisional basis while request processing continues. It alerts the client to wait for a final response. The message consists only of the status line and optional header fields, and is terminated by an empty line. As the HTTP/1.0 standard did not define any 1xx status codes, servers must not[note 1] send a 1xx response to an HTTP/1.0 compliant client except under experimental conditions.
- 100 Continue
- The server has received the request headers and the client should proceed to send the request body (in the case of a request for which a body needs to be sent; for example, a POST request). Sending a large request body to a server after a request has been rejected for inappropriate headers would be inefficient. To have a server check the request’s headers, a client must send
Expect: 100-continue
as a header in its initial request and receive a100 Continue
status code in response before sending the body. If the client receives an error code such as 403 (Forbidden) or 405 (Method Not Allowed) then it should not send the request’s body. The response417 Expectation Failed
indicates that the request should be repeated without theExpect
header as it indicates that the server does not support expectations (this is the case, for example, of HTTP/1.0 servers).[2] - 101 Switching Protocols
- The requester has asked the server to switch protocols and the server has agreed to do so.
- 102 Processing (WebDAV; RFC 2518)
- A WebDAV request may contain many sub-requests involving file operations, requiring a long time to complete the request. This code indicates that the server has received and is processing the request, but no response is available yet. [3] This prevents the client from timing out and assuming the request was lost. The status code is deprecated.[4]
- 103 Early Hints (RFC 8297)
- Used to return some response headers before final HTTP message.[5]
2xx success
This class of status codes indicates the action requested by the client was received, understood, and accepted.[1]
- 200 OK
- Standard response for successful HTTP requests. The actual response will depend on the request method used. In a GET request, the response will contain an entity corresponding to the requested resource. In a POST request, the response will contain an entity describing or containing the result of the action.
- 201 Created
- The request has been fulfilled, resulting in the creation of a new resource.[6]
- 202 Accepted
- The request has been accepted for processing, but the processing has not been completed. The request might or might not be eventually acted upon, and may be disallowed when processing occurs.
- 203 Non-Authoritative Information (since HTTP/1.1)
- The server is a transforming proxy (e.g. a Web accelerator) that received a 200 OK from its origin, but is returning a modified version of the origin’s response.[7][8]
- 204 No Content
- The server successfully processed the request, and is not returning any content.
- 205 Reset Content
- The server successfully processed the request, asks that the requester reset its document view, and is not returning any content.
- 206 Partial Content
- The server is delivering only part of the resource (byte serving) due to a range header sent by the client. The range header is used by HTTP clients to enable resuming of interrupted downloads, or split a download into multiple simultaneous streams.
- 207 Multi-Status (WebDAV; RFC 4918)
- The message body that follows is by default an XML message and can contain a number of separate response codes, depending on how many sub-requests were made.[9]
- 208 Already Reported (WebDAV; RFC 5842)
- The members of a DAV binding have already been enumerated in a preceding part of the (multistatus) response, and are not being included again.
- 226 IM Used (RFC 3229)
- The server has fulfilled a request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.[10]
3xx redirection
This class of status code indicates the client must take additional action to complete the request. Many of these status codes are used in URL redirection.[1]
A user agent may carry out the additional action with no user interaction only if the method used in the second request is GET or HEAD. A user agent may automatically redirect a request. A user agent should detect and intervene to prevent cyclical redirects.[11]
- 300 Multiple Choices
- Indicates multiple options for the resource from which the client may choose (via agent-driven content negotiation). For example, this code could be used to present multiple video format options, to list files with different filename extensions, or to suggest word-sense disambiguation.
- 301 Moved Permanently
- This and all future requests should be directed to the given URI.
- 302 Found (Previously «Moved temporarily»)
- Tells the client to look at (browse to) another URL. The HTTP/1.0 specification (RFC 1945) required the client to perform a temporary redirect with the same method (the original describing phrase was «Moved Temporarily»),[12] but popular browsers implemented 302 redirects by changing the method to GET. Therefore, HTTP/1.1 added status codes 303 and 307 to distinguish between the two behaviours.[11]
- 303 See Other (since HTTP/1.1)
- The response to the request can be found under another URI using the GET method. When received in response to a POST (or PUT/DELETE), the client should presume that the server has received the data and should issue a new GET request to the given URI.
- 304 Not Modified
- Indicates that the resource has not been modified since the version specified by the request headers If-Modified-Since or If-None-Match. In such case, there is no need to retransmit the resource since the client still has a previously-downloaded copy.
- 305 Use Proxy (since HTTP/1.1)
- The requested resource is available only through a proxy, the address for which is provided in the response. For security reasons, many HTTP clients (such as Mozilla Firefox and Internet Explorer) do not obey this status code.
- 306 Switch Proxy
- No longer used. Originally meant «Subsequent requests should use the specified proxy.»
- 307 Temporary Redirect (since HTTP/1.1)
- In this case, the request should be repeated with another URI; however, future requests should still use the original URI. In contrast to how 302 was historically implemented, the request method is not allowed to be changed when reissuing the original request. For example, a POST request should be repeated using another POST request.
- 308 Permanent Redirect
- This and all future requests should be directed to the given URI. 308 parallel the behaviour of 301, but does not allow the HTTP method to change. So, for example, submitting a form to a permanently redirected resource may continue smoothly.
4xx client errors
This class of status code is intended for situations in which the error seems to have been caused by the client. 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.
- 400 Bad Request
- The server cannot or will not process the request due to an apparent client error (e.g., malformed request syntax, size too large, invalid request message framing, or deceptive request routing).
- 401 Unauthorized
- Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource. See Basic access authentication and Digest access authentication. 401 semantically means «unauthorised», the user does not have valid authentication credentials for the target resource.
- Some sites incorrectly issue HTTP 401 when an IP address is banned from the website (usually the website domain) and that specific address is refused permission to access a website.[citation needed]
- 402 Payment Required
- Reserved for future use. The original intention was that this code might be used as part of some form of digital cash or micropayment scheme, as proposed, for example, by GNU Taler,[14] but that has not yet happened, and this code is not widely used. Google Developers API uses this status if a particular developer has exceeded the daily limit on requests.[15] Sipgate uses this code if an account does not have sufficient funds to start a call.[16] Shopify uses this code when the store has not paid their fees and is temporarily disabled.[17] Stripe uses this code for failed payments where parameters were correct, for example blocked fraudulent payments.[18]
- 403 Forbidden
- The request contained valid data and was understood by the server, but the server is refusing action. This may be due to the user not having the necessary permissions for a resource or needing an account of some sort, or attempting a prohibited action (e.g. creating a duplicate record where only one is allowed). This code is also typically used if the request provided authentication by answering the WWW-Authenticate header field challenge, but the server did not accept that authentication. The request should not be repeated.
- 404 Not Found
- The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.
- 405 Method Not Allowed
- A request method is not supported for the requested resource; for example, a GET request on a form that requires data to be presented via POST, or a PUT request on a read-only resource.
- 406 Not Acceptable
- The requested resource is capable of generating only content not acceptable according to the Accept headers sent in the request. See Content negotiation.
- 407 Proxy Authentication Required
- The client must first authenticate itself with the proxy.
- 408 Request Timeout
- The server timed out waiting for the request. According to HTTP specifications: «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
- Indicates that the request could not be processed because of conflict in the current state of the resource, such as an edit conflict between multiple simultaneous updates.
- 410 Gone
- Indicates that the resource requested was previously in use but is no longer available and will not be available again. This should be used when a resource has been intentionally removed and the resource should be purged. Upon receiving a 410 status code, the client should not request the resource in the future. Clients such as search engines should remove the resource from their indices. Most use cases do not require clients and search engines to purge the resource, and a «404 Not Found» may be used instead.
- 411 Length Required
- The request did not specify the length of its content, which is required by the requested resource.
- 412 Precondition Failed
- The server does not meet one of the preconditions that the requester put on the request header fields.
- 413 Payload Too Large
- The request is larger than the server is willing or able to process. Previously called «Request Entity Too Large» in RFC 2616.[19]
- 414 URI Too Long
- The URI provided was too long for the server to process. Often the result of too much data being encoded as a query-string of a GET request, in which case it should be converted to a POST request. Called «Request-URI Too Long» previously in RFC 2616.[20]
- 415 Unsupported Media Type
- The request entity has a media type which the server or resource does not support. For example, the client uploads an image as image/svg+xml, but the server requires that images use a different format.
- 416 Range Not Satisfiable
- The client has asked for a portion of the file (byte serving), but the server cannot supply that portion. For example, if the client asked for a part of the file that lies beyond the end of the file. Called «Requested Range Not Satisfiable» previously RFC 2616.[21]
- 417 Expectation Failed
- The server cannot meet the requirements of the Expect request-header field.[22]
- 418 I’m a teapot (RFC 2324, RFC 7168)
- This code was defined in 1998 as one of the traditional IETF April Fools’ jokes, in RFC 2324, Hyper Text Coffee Pot Control Protocol, and is not expected to be implemented by actual HTTP servers. The RFC specifies this code should be returned by teapots requested to brew coffee.[23] This HTTP status is used as an Easter egg in some websites, such as Google.com’s «I’m a teapot» easter egg.[24][25][26] Sometimes, this status code is also used as a response to a blocked request, instead of the more appropriate 403 Forbidden.[27][28]
- 421 Misdirected Request
- The request was directed at a server that is not able to produce a response (for example because of connection reuse).
- 422 Unprocessable Entity
- The request was well-formed but was unable to be followed due to semantic errors.[9]
- 423 Locked (WebDAV; RFC 4918)
- The resource that is being accessed is locked.[9]
- 424 Failed Dependency (WebDAV; RFC 4918)
- The request failed because it depended on another request and that request failed (e.g., a PROPPATCH).[9]
- 425 Too Early (RFC 8470)
- Indicates that the server is unwilling to risk processing a request that might be replayed.
- 426 Upgrade Required
- The client should switch to a different protocol such as TLS/1.3, given in the Upgrade header field.
- 428 Precondition Required (RFC 6585)
- The origin server requires the request to be conditional. Intended to prevent the ‘lost update’ problem, where a client GETs a resource’s state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.[29]
- 429 Too Many Requests (RFC 6585)
- The user has sent too many requests in a given amount of time. Intended for use with rate-limiting schemes.[29]
- 431 Request Header Fields Too Large (RFC 6585)
- The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large.[29]
- 451 Unavailable For Legal Reasons (RFC 7725)
- A server operator has received a legal demand to deny access to a resource or to a set of resources that includes the requested resource.[30] The code 451 was chosen as a reference to the novel Fahrenheit 451 (see the Acknowledgements in the RFC).
5xx server errors
The server failed to fulfil a request.
Response status codes beginning with the digit «5» indicate cases in which the server is aware that it has encountered an error or is otherwise 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 indicate whether it is a temporary or permanent condition. Likewise, user agents should display any included entity to the user. These response codes are applicable to any request method.
- 500 Internal Server Error
- A generic error message, given when an unexpected condition was encountered and no more specific message is suitable.
- 501 Not Implemented
- The server either does not recognize the request method, or it lacks the ability to fulfil the request. Usually this implies future availability (e.g., a new feature of a web-service API).
- 502 Bad Gateway
- The server was acting as a gateway or proxy and received an invalid response from the upstream server.
- 503 Service Unavailable
- The server cannot handle the request (because it is overloaded or down for maintenance). Generally, this is a temporary state.[31]
- 504 Gateway Timeout
- The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.
- 505 HTTP Version Not Supported
- The server does not support the HTTP version used in the request.
- 506 Variant Also Negotiates (RFC 2295)
- Transparent content negotiation for the request results in a circular reference.[32]
- 507 Insufficient Storage (WebDAV; RFC 4918)
- The server is unable to store the representation needed to complete the request.[9]
- 508 Loop Detected (WebDAV; RFC 5842)
- The server detected an infinite loop while processing the request (sent instead of 208 Already Reported).
- 510 Not Extended (RFC 2774)
- Further extensions to the request are required for the server to fulfil it.[33]
- 511 Network Authentication Required (RFC 6585)
- The client needs to authenticate to gain network access. Intended for use by intercepting proxies used to control access to the network (e.g., «captive portals» used to require agreement to Terms of Service before granting full Internet access via a Wi-Fi hotspot).[29]
Unofficial codes
The following codes are not specified by any standard.
- 419 Page Expired (Laravel Framework)
- Used by the Laravel Framework when a CSRF Token is missing or expired.
- 420 Method Failure (Spring Framework)
- A deprecated response used by the Spring Framework when a method has failed.[34]
- 420 Enhance Your Calm (Twitter)
- Returned by version 1 of the Twitter Search and Trends API when the client is being rate limited; versions 1.1 and later use the 429 Too Many Requests response code instead.[35] The phrase «Enhance your calm» comes from the 1993 movie Demolition Man, and its association with this number is likely a reference to cannabis.[citation needed]
- 430 Request Header Fields Too Large (Shopify)
- Used by Shopify, instead of the 429 Too Many Requests response code, when too many URLs are requested within a certain time frame.[36]
- 450 Blocked by Windows Parental Controls (Microsoft)
- The Microsoft extension code indicated when Windows Parental Controls are turned on and are blocking access to the requested webpage.[37]
- 498 Invalid Token (Esri)
- Returned by ArcGIS for Server. Code 498 indicates an expired or otherwise invalid token.[38]
- 499 Token Required (Esri)
- Returned by ArcGIS for Server. Code 499 indicates that a token is required but was not submitted.[38]
- 509 Bandwidth Limit Exceeded (Apache Web Server/cPanel)
- The server has exceeded the bandwidth specified by the server administrator; this is often used by shared hosting providers to limit the bandwidth of customers.[39]
- 529 Site is overloaded
- Used by Qualys in the SSLLabs server testing API to signal that the site can’t process the request.[40]
- 530 Site is frozen
- Used by the Pantheon Systems web platform to indicate a site that has been frozen due to inactivity.[41]
- 598 (Informal convention) Network read timeout error
- Used by some HTTP proxies to signal a network read timeout behind the proxy to a client in front of the proxy.[42]
- 599 Network Connect Timeout Error
- An error used by some HTTP proxies to signal a network connect timeout behind the proxy to a client in front of the proxy.
Internet Information Services
Microsoft’s Internet Information Services (IIS) web server expands the 4xx error space to signal errors with the client’s request.
- 440 Login Time-out
- The client’s session has expired and must log in again.[43]
- 449 Retry With
- The server cannot honour the request because the user has not provided the required information.[44]
- 451 Redirect
- Used in Exchange ActiveSync when either a more efficient server is available or the server cannot access the users’ mailbox.[45] The client is expected to re-run the HTTP AutoDiscover operation to find a more appropriate server.[46]
IIS sometimes uses additional decimal sub-codes for more specific information,[47] however these sub-codes only appear in the response payload and in documentation, not in the place of an actual HTTP status code.
nginx
The nginx web server software expands the 4xx error space to signal issues with the client’s request.[48][49]
- 444 No Response
- Used internally[50] to instruct the server to return no information to the client and close the connection immediately.
- 494 Request header too large
- Client sent too large request or too long header line.
- 495 SSL Certificate Error
- An expansion of the 400 Bad Request response code, used when the client has provided an invalid client certificate.
- 496 SSL Certificate Required
- An expansion of the 400 Bad Request response code, used when a client certificate is required but not provided.
- 497 HTTP Request Sent to HTTPS Port
- An expansion of the 400 Bad Request response code, used when the client has made a HTTP request to a port listening for HTTPS requests.
- 499 Client Closed Request
- Used when the client has closed the request before the server could send a response.
Cloudflare
Cloudflare’s reverse proxy service expands the 5xx series of errors space to signal issues with the origin server.[51]
- 520 Web Server Returned an Unknown Error
- The origin server returned an empty, unknown, or unexpected response to Cloudflare.[52]
- 521 Web Server Is Down
- The origin server refused connections from Cloudflare. Security solutions at the origin may be blocking legitimate connections from certain Cloudflare IP addresses.
- 522 Connection Timed Out
- Cloudflare timed out contacting the origin server.
- 523 Origin Is Unreachable
- Cloudflare could not reach the origin server; for example, if the DNS records for the origin server are incorrect or missing.
- 524 A Timeout Occurred
- Cloudflare was able to complete a TCP connection to the origin server, but did not receive a timely HTTP response.
- 525 SSL Handshake Failed
- Cloudflare could not negotiate a SSL/TLS handshake with the origin server.
- 526 Invalid SSL Certificate
- Cloudflare could not validate the SSL certificate on the origin web server. Also used by Cloud Foundry’s gorouter.
- 527 Railgun Error
- Error 527 indicates an interrupted connection between Cloudflare and the origin server’s Railgun server.[53]
- 530
- Error 530 is returned along with a 1xxx error.[54]
AWS Elastic Load Balancer
Amazon’s Elastic Load Balancing adds a few custom return codes
- 460
- Client closed the connection with the load balancer before the idle timeout period elapsed. Typically when client timeout is sooner than the Elastic Load Balancer’s timeout.[55]
- 463
- The load balancer received an X-Forwarded-For request header with more than 30 IP addresses.[55]
- 464
- Incompatible protocol versions between Client and Origin server.[55]
- 561 Unauthorized
- An error around authentication returned by a server registered with a load balancer. You configured a listener rule to authenticate users, but the identity provider (IdP) returned an error code when authenticating the user.[55]
Caching warning codes (obsoleted)
The following caching related warning codes were specified under RFC 7234. Unlike the other status codes above, these were not sent as the response status in the HTTP protocol, but as part of the «Warning» HTTP header.[56][57]
Since this «Warning» header is often neither sent by servers nor acknowledged by clients, this header and its codes were obsoleted by the HTTP Working Group in 2022 with RFC 9111.[58]
- 110 Response is Stale
- The response provided by a cache is stale (the content’s age exceeds a maximum age set by a Cache-Control header or heuristically chosen lifetime).
- 111 Revalidation Failed
- The cache was unable to validate the response, due to an inability to reach the origin server.
- 112 Disconnected Operation
- The cache is intentionally disconnected from the rest of the network.
- 113 Heuristic Expiration
- The cache heuristically chose a freshness lifetime greater than 24 hours and the response’s age is greater than 24 hours.
- 199 Miscellaneous Warning
- Arbitrary, non-specific warning. The warning text may be logged or presented to the user.
- 214 Transformation Applied
- Added by a proxy if it applies any transformation to the representation, such as changing the content encoding, media type or the like.
- 299 Miscellaneous Persistent Warning
- Same as 199, but indicating a persistent warning.
See also
- Custom error pages
- List of FTP server return codes
- List of HTTP header fields
- List of SMTP server return codes
- Common Log Format
Explanatory notes
- ^ Emphasised words and phrases such as must and should represent interpretation guidelines as given by RFC 2119
References
- ^ a b c «Hypertext Transfer Protocol (HTTP) Status Code Registry». Iana.org. Archived from the original on December 11, 2011. Retrieved January 8, 2015.
- ^ Fielding, Roy T. «RFC 9110: HTTP Semantics and Content, Section 10.1.1 «Expect»«.
- ^ Goland, Yaronn; Whitehead, Jim; Faizi, Asad; Carter, Steve R.; Jensen, Del (February 1999). HTTP Extensions for Distributed Authoring – WEBDAV. IETF. doi:10.17487/RFC2518. RFC 2518. Retrieved October 24, 2009.
- ^ «102 Processing — HTTP MDN». 102 status code is deprecated
- ^ Oku, Kazuho (December 2017). An HTTP Status Code for Indicating Hints. IETF. doi:10.17487/RFC8297. RFC 8297. Retrieved December 20, 2017.
- ^ Stewart, Mark; djna. «Create request with POST, which response codes 200 or 201 and content». Stack Overflow. Archived from the original on October 11, 2016. Retrieved October 16, 2015.
- ^ «RFC 9110: HTTP Semantics and Content, Section 15.3.4».
- ^ «RFC 9110: HTTP Semantics and Content, Section 7.7».
- ^ a b c d e Dusseault, Lisa, ed. (June 2007). HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV). IETF. doi:10.17487/RFC4918. RFC 4918. Retrieved October 24, 2009.
- ^ Delta encoding in HTTP. IETF. January 2002. doi:10.17487/RFC3229. RFC 3229. Retrieved February 25, 2011.
- ^ a b «RFC 9110: HTTP Semantics and Content, Section 15.4 «Redirection 3xx»«.
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Any attempt to brew coffee with a teapot should result in the error code «418 I’m a teapot». The resulting entity body MAY be short and stout.
- ^ I’m a teapot
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- ^ «Error 530». Cloudflare. Retrieved November 1, 2019.
- ^ a b c d «Troubleshoot Your Application Load Balancers – Elastic Load Balancing». docs.aws.amazon.com. Retrieved May 17, 2023.
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- ^ «RFC 9111: HTTP Caching, Section 5.5 «Warning»«. June 2022.
External links
- «RFC 9110: HTTP Semantics and Content, Section 15 «Status Codes»«.
- Hypertext Transfer Protocol (HTTP) Status Code Registry at the Internet Assigned Numbers Authority
- MDN status code reference at mozilla.org
Ошибка 412 относится, как к обычному пользователю, так и к вебмастеру. Только, если речь идет о простом пользователе – особо делать нечего, т.к. все зависит от администратора сайта. Разберемся, что означает данная ошибка, когда она возникает и при каких условиях, а также как исправить ошибку 412 Precondition Failed.
Что такое «Ошибка 412 Precondition Failed» и когда она возникает?
Ошибка 412 Precondition Failed (Error 412 Precondition Failed) – это уведомление со стороны HTTP, которое указывает на то, что доступ к ресурсу был отклонен. Ресурсом может быть не только сайт в целом, но и отдельные элементы: изображения, аудио и видео контент, отдельные скрипты или плагины.
Следует отметить, что ошибка 412 Precondition Failed возникает в двух случаях: в клиентском браузере и на стороне администратора сайта. В первом случае, если вы уверены, что сайт должен открываться – следует почистить куки в вашем браузере. Во втором – скорее всего вы выполняли изменения на сайте. Часто, ошибка 412 возникает у администраторов, сервер которых использует систему Windows.
Для администратора сайта: причины ошибки 412
- Ошибка 412 возникает после изменений на сайте, часто изменения глобальные. Для примера, вы решили изменить код сайта, чтобы установить водяные знаки на все изображения в постах сайта. При редактировании поста может возникнуть ошибка 412. Данный случай связан с Windows Live Writer. Система выдает ошибку 412 Precondition Failed – не выполнено предварительное условие.
- При использовании Windows Server 2008 в пакете Standart SP 1 в журнале вы можете обнаружить ошибку 412. Связано это может быть не только с изменениями на самом сайте, но и банально – смена железа. Обновление в SP 2 скорее всего ничего не решит. Что делать и как исправить ошибку 412 вебмастеру читаем в следующем разделе.
- Изменения с помощью плагинов и изменения в теме сайта. При изменении дизайна сайта пакетом через административную панель, например, на WordPress. Т.е. вы приобрели пакет шаблона и попытались установить новую тему. Также и с плагинами. К слову, часто плагин WP Super Cache приводит к возникновению ошибки 412, причем не только на видимой пользователю части, но и в административной. При этом, это результат конфликта между настройками кеширования на самом сервере, и настройками установленного плагина.
Причины ошибки 412 со стороны пользователя
Со стороны пользователя ошибка возникает только в одном случае – сбой в браузере. Скорее всего, почти все сайты, которые вы раньше открывали, перестанут работать. Если проблема только с одним сайтом – это не ваша проблема. Все просто.
Как исправить ошибку 412 Precondition Failed?
Меньше всего действий нужно предпринимать со стороны пользователя. Именно поэтому, начнем список с решений для обычного пользователя. Кстати, в выдаче Google есть сайт, на котором любая ошибка, даже ошибка 404, лечится чисткой реестра или переустановкой системы Windows. Ребят, это полная чушь. В решении ошибки 412 никаких манипуляций с системой со стороны пользователя делать не стоит.
Исправление ошибки 412 обычному пользователю
Как уже упоминалось выше, если при входе на сайт вы видите ошибку 412, не паникуйте. В первую очередь, пробуйте самое простое – перезапустите ваш браузер. Не помогло? В этом случае нужно почистить куки. Обычно пользователи годами этого не делают. Можно почистить сразу все браузеры с помощью программы CCleaner – программа бесплатная. Просто скачайте, установите и в разделе чистки выполните очистку, пользуясь подсказками.
Как почистить куки без программ, чтобы удалить ошибку 412 в браузере? Перечислим несколько популярных браузеров и пути для поиска функции в программе. Внимание: удаляются все данные сайтов, включая сохраненные пароли (если удалять комплексом куки, историю, автозаполнение и т.д.).
Opera. Нажимаем на иконку Оперы в левом верхнем углу, затем ищем «Настройки». Затем выбираем пункты: Безопасность – Все файлы cookies – выбираем все – нажимаем удалить.
Google Chrome. В новой пустой вкладке нажимаем комбинацию клавиш – Shift+Ctrl+Del. Ставим все галочки, выбираем время «Очистить за все время» и удаляем.
Mozilla Firefox. В правом верхнем углу есть три полоски (нажимаем) и ищем пункт «Настройки». Вы увидите страницу, где в левой колонке нужно выбрать «Приватность и Защита» — нажимаем. Смотрим раздел «Куки и данные сайтов» и нажимаем там «Удалить данные». Подтверждаем – «Удалить».
Что делать администратору сайта?
- В первом случае, который описан выше, попробуйте просто восстановить сайт из резервной копии. Обычно, любой уважающий себя хостинг, делает ежедневные резервные копии. Это можно сделать, если вы сделали много правок на сайте и не знаете, какая именно правка или какие изменения вызвали ошибку. Совет на будущее – сделали правку, проверили сайт. Ошибка 412 Precondition Failed уйдет после восстановления из резервной копии. На всякий случай, восстановить нужно, как сайт, так и БД.
- Если ошибка 412 возникла на системе Windows Server 2008, можно переустановить систему. Но более удачное решение – установить Update Если у вас стоит SP 1, обновление до SP 2 ничего не изменит. Чтобы исправить ошибку 412 также можно просто переустановить систему с нуля. Данные манипуляции следует делать, если вы на 100% уверены, что ошибка не связана с последними изменениями на сайте, которые вы делали.
- В случае обнаружения ошибки 412 на сайте нужно сразу пройти в консоль Google. Проверьте, какие страницы привели первоначально к сбою. Возможно, если ошибка возникла давно, эти страницы выпали из поиска. Это грустно. Придется поработать. Начните с отката изменений, например, удалите последние плагины. Параллельно нужно тестировать сайт на разных устройствах.
Вообще, ошибка 412 у вебмастера возникает ввиду не аккуратного редактирования кода, поэтому всегда делайте резервную копию перед любыми правками. Если остались вопросы – напишите в комментариях, отвечаю быстро. До связи.
One or more conditions given in the request header fields evaluated to false when tested on the server.
This response code allows the client to place preconditions on the current resource state (its current representations and metadata) and, thus, prevent the request method from being applied if the target resource is in an unexpected state.
- Source: RFC7232 Section 4.2
412 CODE REFERENCES
Rails HTTP Status Symbol :precondition_failed
Go HTTP Status Constant http.StatusPreconditionFailed
Symfony HTTP Status Constant Response::HTTP_PRECONDITION_FAILED
Python2 HTTP Status Constant httplib.PRECONDITION_FAILED
Python3+ HTTP Status Constant http.client.PRECONDITION_FAILED
Python3.5+ HTTP Status Constant http.HTTPStatus.PRECONDITION_FAILED
When is a 412 status code used?
An HTTP 412 status code is used for HTTP requests are not HTTP method HEAD or HTTP method GET.
When the 412 precondition failed error message is received, the client will know that one or more of the conditions in the request has failed and the resource will not be retrieved in the expected format or state.
Will search engines index a URL with a 412 status code?
No. Search engines like Google will not index a URL with the HTTP 412 precondition failed status code. That means that URLs that have been previously indexed but are now returning a 412 response status will likely suffer a loss in their search result rankings.
412 status code example
Want to see a 412 response code in action? Check out the 412 example below. In this example, the client is requesting to leave a comment on an article but only wants their response to be recorded if the article hasn’t been updated since they last viewed it.
If this article has been modified, the server will respond with a 412 precondition failed status error to demonstrate that the client’s request hasn’t been fulfilled.
Request
POST /examplearticle/update?postid=123&task=reply HTTP/1:1
Host: www.example.com
If-unmodified-since: 13 March 2023 0:00:00 GMT
Content-type: text/plain
Content length: 30
<message body from client>
Response
HTTP/1:1 412 Precondition Failed
Content type: text/plain
Content length: 60
<html>
<head>
<title> Article Update Error <title>
<head>
<body>
<p> This article has been updated since you recorded your comment, so your response will not be posted.<>;p>
<body>
</html>
Which browsers are compatible with a 412 response code?
The following browsers will issue an HTTP 412 response code:
- Google Chrome
- Microsoft Edge
- Firefox
- Opera
- Safari
- Chrome Android
- Safari on iOS
- Samsung Internet
WebView Android
Additional resources
- Learn about web development
- Learn about SEO
- Web development services from WebFX
- SEO services from WebFX
- MDN Web Docs
- W3Schools
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