To help you identify what each HTTP status code is, here is a list I have summarized of Wikipedia :
Category 1xx - Informative
This class of status code indicates an interim response, consisting only of Status-Line and optional headers, and is terminated by an empty line. Since HTTP / 1.0 does not define all 1xx status codes, servers should not send an 1xx response to an HTTP / 1.0 client except under experimental conditions.
- 100 Continue
This means that the server has received the request headers, and that the client must proceed to send the request body (in the case of a request to which a body should be sent, for example, a POST request). If the request body is large, sending them to a server when the request has already been rejected based on inappropriate headers is inefficient. To have a server check if the request can be accepted based on the request for headers alone, the customer must send Wait: 100-continue as a header in their initial order and verify that the 100 Resume status code is received in response before permanent (or receive 417 Expectation failed and not continue).
- 101 Changing Protocols
This means that the requester has asked the server to change protocols and the server is acknowledging that it will. 102 Processing (WebDAV) (RFC 2518) Because a WebDAV request can contain many subrequests that involve file operations, it may take a long time to complete the request. This code indicates that the server has received and is processing the request, but no response is yet available. This prevents the client from timing out and assuming that the order has been lost.
- 122 Request-URI too long
This is a standard IE7 code only does not mean that the URI is more than a maximum of 2083 characters. (See code 414).
Category 2xx - Success
This class of status codes indicates the action requested by the customer was successfully received, understood, accepted and processed.
- 200 OK
Response pattern for successful HTTP requests. The actual response will depend on the request method used. In a GET request, the response will contain an entity that corresponds to the requested resource. In a POST request the response will contain the description of an entity, or containing the result of the action.
- 201 Created
The request has been fulfilled and has resulted in a new feature being created.
- 202 Accepted
The request has been accepted for processing, but processing has not been completed. The request may or may not be implemented as it may be canceled when processing actually occurs.
- Unauthorized 203 (since HTTP / 1.1)
The server processed the request successfully, but is returning information that may be from another source.
- 204 No content
The server processed the request successfully, but is not returning any content.
- 205 Reset
The server processed the request successfully, but is not returning any content. Unlike 204, this response requires the requester to reset the document view.
- 206 Partial Content
The server is only delivering part of the resource due to a header range sent by the client. The range header is used by tools like wget to allow resuming interrupted downloads, or split a download into multiple simultaneous streams.
- 207-Status Multi (WebDAV) (RFC 4918)
The following message body is a message XML and can contain a number of individual response codes, depending on how many sub requests have been made.
Category 3xx - Redirect
The customer must take additional steps to complete the order. This status code class indicates that the action still needs to be taken by the user agent in order to fulfill the request. The required action can be performed by the agent without user interaction 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 five times, as such redirects usually indicate an infinite loop.
- 300 Multiple Choice
Indicates several options for the feature that the customer can track. It, for example, could be used to present different format options for video, list files with different extensions, or disambiguation meaning of the word.
- Moved 301
This and all future requests must be directed to the URI.
- 302 Found
This is an example of good industrial practice contradicting the norm. HTTP / 1.0 specification (RFC 1945) required the client to perform a temporary redirect (what describes original phrase was "Moved Temporarily"), but popular browsers running 302 with the functionality of an 303 See Other. Therefore, it added HTTP / 1.1 status codes 303 and 307 to distinguish between the two behaviors. However, most web applications and frames still use the 302 status code as if it were 303.
- 304 Not Modified
Indicates that the resource has not been modified since the last request. Typically, the client provides an HTTP header as the If-Modified-Since header to provide a time against which to compare. Using this saves bandwidth and reprocessing on the server and client, since only header data should be sent and received compared to the entire page being reprocessed by the server, then sent back using more server and client bandwidth.
- 305 Use Proxy (from HTTP / 1.1)
Many HTTP clients (such as Mozilla and Internet Explorer) may not correctly handle responses with this status code, mainly for security reasons.
- 306 Proxy Switch
It is no longer used.
- 307 Temporary Redirect (from HTTP / 1.1)
At this time, the request must be repeated with another URI, but future requests may still use the original URI. In contrast to 303, the ordering method should not be changed when reissuing the original order. For example, a POST request must be repeated with another POST request.
Category 4xx - Client Error
The status code class 4xx is intended for cases where the customer appears to have made an error. Except when responding to a HEAD request, the server must include an entity that contains an explanation of the error situation, and whether it is a temporary or permanent condition. These status codes apply to any request method. User agents must display any entities added to the user. These are typically the most common error codes encountered during online.
- 400 Invalid Request
Order could not be delivered due to incorrect syntax.
- 401 Unauthorized
Similar to 403 Forbidden, but specifically for use when authentication is possible, but failed or not yet provided. The response must include a www-authenticat field header containing a challenge applicable to the requested resource. See Basic Access Authentication and Digest Access Authentication.
- 402 Payment Required
Reserved for future use. The original intent was that this code could be used as part of some form of digital money or micro payment scheme, but it did not happen, and this code is not used normally.
- 403 Forbidden
The request was a legal request, but the server is refusing to respond to it. Unlike an Unauthorized 401 response, authentication will make no difference.
- 404 Not Found
The requested resource was not found, but may be made available again in the future. Subsequent requests by the customer are allowed. Eventually the requested resource has been removed from the server for some reason but may be reset if necessary.
- 405 Method not allowed
A request made from a resource using an ordering method is not compatible with that resource, for example using GET on a form, which requires the data to be submitted via POST, PUT or use on a read-only resource.
- 406 Not Acceptable
The requested resource is only capable of generating unacceptable content according to the Accept headers sent in the request.
- 407 Proxy Authentication Required
- 408 Timeout Order
The server timed out waiting for the request. According to the W3 HTTP specifications: “The client did not submit a request within the time the server was prepared to wait for the time. The customer can repeat the order without modification any afternoon. "
- 409 Conflict
Indicates that the request could not be processed because of the request conflict, such as an edit conflict.
- 410 Gone
Indicates that the requested feature is no longer available and will not be available again. This should be used when a feature has been intentionally removed and the features must be removed. Upon receiving an 410 status code, the customer should not request the feature again in the future. Customers like search engines should remove the feature from their indexes. Most use cases do not require clients and search engines to purge the feature, and an “404 Not Found” can be used.
- 411 Length Required
The request does 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 conditions that the requester places in the request.
- 413 Request entity too large
The request is larger than the server is willing or able to process.
- 414 Request-URI Too Long
The provided URI was too long for the server to process.
- 415 Unsupported Media Type
The entity has a media type request that the server or resource is not supported. For example, the client loads an image as image / svg + xml, but the server requires images to use a different format.
- 416 Requested from Unsatisfactory Range
The client has requested a part of the file, but the server cannot provide that part. For example, if the customer requested a part of the file that is beyond the end of the file.
- 417 Expectation Failed
The server cannot meet the requirements of the Wait-Request header field.
- 418 I'm a teapot
This code was defined in 1998 as one of the traditional IETF April 1 pranks on the RFC 2324 Hyper Text Coffee Control Protocol, and is not expected to be implemented by real HTTP servers.
- 422 Inaccessible Entity (WebDAV) (RFC 4918)
The request was well formed but was unable to be followed due to semantic errors.
- 423 Closed (WebDAV) (RFC 4918)
The resource being accessed is locked.
- 424 Dependency Failure (WebDAV) (RFC 4918)
The request failed because a previous request failed (for example, a PROPPATCH).
- 425 Unordered Collection (RFC 3648)
Defined in “WebDAV Advanced Collections Protocol” projects, but is not present in the “Web Distributed Authoring and Versioning (WebDAV) Sorted Collections Protocol”.
- 426 Upgrade Required (RFC 2817)
The client must switch to another protocol, such as TLS / 1.0. Answer No. 444 An Nginx HTTP server extension. The server returns no information to the client and closes the connection (useful as a deterrent for malware). With 449 Repeat A Microsoft Extension. The request must be repeated after the appropriate action has been taken.
- 450 Blocked by Windows Parental Controls
An extension of Microsoft. This error is given when Windows Parental Controls are enabled and is blocking access to a particular web page.
- 499 Client Closed Order (used in ERPs / VPSA)
A Nginx HTTP server extension. This code is introduced to log the case when the connection is closed by the client to the HTTP server and processing its request, making the server unable to send the HTTP header back.
Category 5xx - Other Errors
- 500 Internal Server Error
Indicates a server error processing the request. In most cases the permissions of the files or folders of the software or script that the user attempts to access are listed and were not configured at the time of programming / building the site or application. To fix, check the directory where the failed file or resource is located, and this file (as well as all others) obey the following rules:
Folders - chmod 755 (do not use 777)
Files - chmod 644 (do not use 777, only use another if expressly requested at installation)
NOTE: Some applications and / or systems require different permissions, so it is important to check with the script / system creators for the correct permission to use. The example describes how it is performed on Unix-like operating systems. Make analogy as it is performed on systems like Windows (Windows 7, 8, XP among others).
This error can also occur if the file. Your site's htaccess You are modifying the parameters trying to do so using PHP as commands: php_flag or php_value. Remove any entries with these commands from the .htaccess file. If you are going to make PHP modifications to the parameters, use the php.ini file to do this.
- 501 Not implemented
Server does not support enabled functionality yet
- 502 Bad Gateway
As a rule, the error when there is an inaccurate configuration between backend computers, possibly including the web server in the visited site. Before analyzing this issue, you need to clear your browser cache completely. If you are browsing the web and see this issue on all websites you visit, then 1) your internet service provider has a main equipment failure / overload or 2) something is wrong with your internal internet connection, for example. For example, the firewall is not working correctly. If so, only your provider can help. If you are second, you need to fix whatever is preventing you from accessing the Internet. If you only have this issue on some websites you visit, there is probably a problem with the sites. For example, one of the pieces of equipment is failing or overloaded. Contact those responsible for these sites.
- 503 Service Unavailable
The server is down for maintenance or unable to handle resource processing due to system overload. This must be a temporary condition.
- 504 Gateway Time-Out
It is characterized by particular errors of the site in question. It may be that the site is under maintenance or does not exist.
- 505 HTTP Version not supported
Most browsers assume that network servers support 1.x versions of the HTTP protocol. In practice, very old versions like 0.9 are underused today, not only because they provide poor security and lower performance than newer versions of the protocol. So if this error occurs in your network browser, the only option is to upgrade the network server software. If the 1.x request version fails, it may be because the network server is supporting incorrect versions of the 1.x protocol instead of not supporting them.