404, 500, 502, 504, and More Errors on Web Pages, What do they Mean?
Errors on Web Pages
Indeed, you have ever tried to open a web page in the browser and have been pleasantly surprised that you have received an error message instead of the page. Today we will see what these errors mean on web pages and what you can do when you come across one.
Some of these codes are more famous than others, so almost everyone knows the 404 error, but there are more than 60 codes, although not all are errors. We will see what these codes are and their meanings, grouped by type.
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What are Status Codes
Let’s start at the beginning. What are these codes? These are the codes that a server returns, subsequently receiving an HTTP request. Also, that serves to identify if everything has gone well or there has been an error. When everything goes well, you never see any code since this exchange happens between your browser and the server.
For example, when you try to open an image on the Internet, the browser appeals to the server’s image. If altogether goes well, the server will return a code 200 (which means OK), but if the image does not exist, it will produce a code 404 (which means not found). These codes come together into five categories: 100, 200, 300, 400, and 500.
Status Codes 100
Status codes that start with 100 are not errors but merely informational. As a user, you will never see them, but behind the scenes indicate that the request has been customary, and the process continues.
- 100 Continue: instructs the browser to continue making your request
- 101 Switching Protocols indicates to the browser that it accepts the requested protocol change.
- 102 Processing: indicates to the browser that it has received the request and is still processing it.
- 103 Checkpoint: will resume a previously canceled request.
Status Codes 200
These codes also indicate that everything has gone correctly. The request has been received, processed, and returned successfully. Therefore, you will never see them in your browser, as they mean that everything has gone well.
- 200 OK: everything has been deal with correctly.
- 201 Created – The request has been processed, and a new resource has made as a result.
- 202 Accepted – The request has been accepted but has not yet been complete.
- 203 Non-Authoritative Information: Indicates that the request has over, but another server has obtained the resource.
- 204 No Content: The request has been deal with successfully, but the result is empty.
- 205 Reset Content: same as the previous one, but indicating to the browser that it should initialize the page from which the request has made.
- 206 Partial Content: Partially requested content is a return. Useful for resuming downloads that have paused.
- 207 Multi-Status: returns multiple requests at the same time.
- 208 Already Reported: The list of items has already returned, so it is not listed again.
Status Codes 300
Status codes beginning with 300 are related to redirects. Servers use these codes to tell the browser that the page or resource has moved. As a user, you will not see these codes, although a page could automatically redirect you to another.
- 300 Multiple Choices indicates to the browser that there are several alternatives for the content you have requested. For example, a video may be available in different formats or qualities.
- 301 Moved Permanently – The page you are looking for is not here and has permanently moved to a new location.
- 302 Found: indicates that the page or resource is available in another location.
- 303 See Other: same as above.
- 304 Not Modified: indicates to the browser that the page has not modified since the last time it has requested. This way, you can avoid downloading it again, saving bandwidth.
- 305 Use Proxy – This resource is only available from a proxy.
- 306 Switch Proxy: This code is no longer use.
- 307 Temporary Redirect – Tells the browser that this resource or page has been moved but is still available at this address.
- 308 Permanent Redirect – Similar to code 301, the page has permanently relocated.
Status Codes 400
The 400 statuses correspond to client errors, and you will often see them. It is the case of the well-known 404 error, which appears when the page you tried to find does not exist. It is, therefore, a client error (the web address was wrong).
- 400 Bad Request: something has gone wrong with the request. If you get this error, try refreshing the page or updating your browser.
- 401 Unlawful: You do not have the authorization to receive that content.
- 402 Payment Required – deprecated for now.
- 403 Forbidden: the request is correct, but the server refuses to offer you the resource or web page. You may need an account on the service and log in before you can access it.
404 Not Found
The most famous status code of all indicates that the resource is not available on the server. Maybe it was in the past and has been deleted or misspelled the web address. If you receive this error, the address you entered is correct, and nothing is missing or excess. You can also insert the address into the Wayback Machine to see if it existed in the past.
- 405 Method Not Allowed: The use of this method is not allowed.
- 406 Not Acceptable – The request can only generate a content type other than the one specified as acceptable.
- 407 Proxy Authentication Required: The client is required to identify himself through a proxy.
- 408 Request Timeout: The server has spent too long waiting for a response from the client.
- 409 Conflict: The request could not remain finalized because there was a problem with it.
- 410 Gone: that page does not exist. Search engines use this code like Google, which uses the information to remove content from their database.
- 411 Length Required: The client was supposed to indicate the content’s length but did not.
- 412 Precondition Failed: The server looks after not meet the preconditions indicated in the request.
- 413 Payload Too Large: The request is too long, and the server refuses to process it.
- 414 URI Too Long: The web address is too long. If you receive this error, you will hardly solve it because it is not your problem, but the page that generated the link.
- 415 Unsupported Media Type – The type of file received is different than expected.
- 416 Range Not Satisfiable: The client has requested a portion of a resource that is incorrect.
- 417 Expectation Failed: The server cannot come across the expectations of the header.
- 418 I’m a teapot: it’s a status code born as an April’s Fools joke. You can receive one by visiting this website.
- 421 Misdirected Request: The server is unable to produce a response.
- 422 Unprocessable Entity: the request was successful but had some semantic error.
- 423 Locked – This resource is locked.
- 424 Failed Dependency: This resource depends on another answer, which failed.
- 426 Upgrade Required – Customer must use a different protocol.
- 428 Precondition Required: the server requires that the request be conditional.
- 431 Request Header Fields Too Large: The header or some of the header fields are too large.
- 452 Unavailable for Legal Reasons: the server denies access to this resource for legal reasons.
Status Codes 500
While 400 status codes involve errors from the client (from you, your browser, or your connection), 500 errors are errors from the server-side. The server may have a temporary problem, and there isn’t much you can do except try again later.
500 Internal Server Error
Second in popularity after the 404 error, the 500 error is a generic error indicating a problem with the server. Nothing more concrete is specified, so the problem can be of any kind, from being overloaded to currently making some internal changes so that something has stopped working. As a user, you can wait and try again later.
- 501 Not Implemented: the server has not yet implemented the requested method, although it is likely to be added in the future.
- 502 Bad Gateway: the server is temporary as a proxy or gateway and has received an invalid response from the other server.
503 Service Unavailable
The 500 error is more generic, saying that something is wrong with the server, but the 503 states that the server is not available at the moment. It may be because you remain overloaded with too many requests or because you are currently undergoing maintenance. Try again in a few minutes.
- 504 Gateway Timeout – The server acted as a gateway or proxy and received no response from the server.
- 505 HTTP Version Not Supported – The server does not support the requested version of the HTTP protocol.
- 506 Variant Also Negotiates the request results in a request with circular references.
- 507 Not enough Storage: The server does not have enough space to complete the request.
- 508 Loop Detected – The server has detected an infinite loop.
- 510 Not Extended: the server requires extensions to complete the request.
- 511 Network Authentication Required: The client needs to identify himself.
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