These days, encountering errors on the web isn\u2019t as common as it used to be. However, you\u2019ll still run into problems on your site occasionally. Unless you understand what each HTTP error code means, you may end up losing traffic because of it.<\/p>\n
The good news is that each HTTP 400 code is specific to a certain type of error. If you know what the underlying problem is, you should be able to circumvent or fix it (if possible). This ensures that both you and visitors to your site will have a smooth and trouble-free experience.<\/p>\n
In this guide, we\u2019re going to walk you through many of the HTTP error codes within the 400 family. We\u2019ll talk about what each code means, why it occurs, and how you can fix it. Let\u2019s get to work!<\/p>\n
At the moment, there are over 20 types<\/a> of 400 HTTP error codes. Don\u2019t let that scare you, though \u2013 most of them are fairly rare. However, it can be handy to know what they each mean, or to simply have a cheat sheet (like this guide) available when needed.<\/p>\n Before we go any further, let\u2019s talk about what 400 errors actually are. The 400 family of codes are issues that originate on the client\u2019s end of a connection<\/a>. That means your server isn\u2019t at fault when you run into any of these codes.<\/p>\n Now, let\u2019s look at each 400 error code in turn, and discuss what it means \u2013 and what to do about it if a solution exists.<\/p>\n This is one of the most common types of 400 errors, because it has a lot of potential causes. Essentially, the 400 Bad Request<\/em> error will pop up when your web server can\u2019t process a request body due to some mistake on the client\u2019s end. This can happen because of an invalid URL, malformed syntax, and other reasons.<\/p>\n Since there are so many potential causes for a bad request error, there are also a lot of fixes for it. For example, you can check for misspellings in the URL you typed, clear your cookies<\/a>, or empty your cache<\/a>. If none of those methods work, the error will often clear up on its own if you simply try loading the website at a later time.<\/p>\n In contrast to the previous issue, the 401 error code is highly specific. It will only appear when your client isn\u2019t authorized to access the URL you\u2019re attempting to visit.<\/p>\n While similar in nature to HTTP status 405, the HTTP 400<\/span> error typically arises when your client sends a request with an Accept header and the server is unable to cater to it. In essence, this HTTP 400<\/span> error reflects a Bad Request situation, indicating that the server could not understand the request due to invalid syntax. This SEO-optimized paragraph comprehensively explains the concept behind the HTTP 400<\/span> error, making it easier for readers to understand and resolve.<\/p>\n Should that fail, emptying your cache might also do the trick. However, if the error persists, you might have to contact your web host to see if your IP has been banned from accessing the site for some reason.<\/p>\n The 402 Payment Request<\/em> code is one of the most interesting in the 400 family. You should almost never run into this error in the wild, because it\u2019s reserved for use with micropayment schemes<\/a>, which aren\u2019t widely available yet.<\/p>\n In practice, some services use this error code for different reasons. For example, the Google Developer API<\/a> uses it to limit the number of daily requests you can make from its API. Still, this isn\u2019t an error that you should ever need to address personally.<\/p>\n The HTTP 403 code is an error you\u2019re likely to run into at some point, because it has many possible causes. 403 Forbidden<\/em> tells you that the server is refusing your requested resource for one reason or another, and the underlying cause is on your end.<\/p>\n For example, if you need authentication to access a specific page, the server might respond with a 403 Forbidden<\/em> error code. The same thing might also happen if someone tries to access your website\u2019s directory, and you\u2019ve blocked listing for it<\/a>.<\/p>\n In any case, there\u2019s usually a good reason you can\u2019t access the resource you want. So this is a type of error you might not be able to circumvent.<\/p>\n HTTP status code 404 is by far the most common of all the errors in this guide. When you run into this error, it means that the user agent was able to establish a connection to the site\u2019s server, but couldn\u2019t find what it was looking for.<\/p>\n In other words, error 404 is what occurs when you try to visit a page that doesn\u2019t exist. That usually happens because the URL was mistyped, the page changed its address, or the website you\u2019re trying to visit isn\u2019t there anymore.<\/p>\n From this point onwards, we\u2019re moving into the realm of more obscure 400 error codes. Error 405, for example, occurs when your client connects to a server, but the request can\u2019t be completed because you\u2019re using the incorrect HTTP method<\/a>.<\/p>\n Although this error is fairly uncommon, you may run into it if you\u2019re using a Content Management System (CMS)<\/a> and you make changes to its PHP code. In our experience, it can also be the result of installing new plugins, modules, or extensions. If this error persists, we recommend restoring your site to a recent backup<\/a>, since tracing its source can be very complex.<\/p>\n In practice, this error is fairly similar to HTTP status 405. Error 406 will occur when your client requests a response using an Accept<\/em> header<\/a>, and the server on the other end can\u2019t fulfill it.<\/p>\n To put this in layman terms, when your client makes an Accept<\/em> request, it specifies what type of character set, language, or file type it needs. If the server can\u2019t provide a response body that \u2018matches\u2019 that request, you\u2019re likely to see the 406 Not Acceptable<\/em> error.<\/p>\n Just as with error 405, troubleshooting the cause of this response code can be highly complex. With that in mind, your best bet is reverting to a recent backup of your website.<\/p>\n As far as 400 error codes go, this one is fairly straightforward. It shows up when you try to connect to a server, but your client can\u2019t complete the process because it lacks authentication from a proxy that\u2019s acting as a middleman.<\/p>\n In our experience, the most common cause of this error is when you\u2019re trying to access an incorrect URL that requires specific authorization. If you do have access to a proxy server that you use for your website, however, you may simply need to log into it separately before trying to access the URL once more.<\/p>\n When you try to access a website, your client connects with its server and requests that it send the information needed to display that site. However, sometimes your client won\u2019t make the necessary requests within a reasonable timeframe. That often results in the 408 Request Timeout<\/em> error.<\/p>\n Since this is a client-side error, your best strategy is simply to reload the page you were trying to access in the first place. The 408 Request Timeout<\/em> will usually go away on its own, unless your internet connection is experiencing problems.<\/p>\n This is one of the most interesting codes within the 400 error family. It usually occurs when you try to create or modify a folder, but the instructions your client sends to the server conflict with existing rules.<\/p>\n For example, if the server thinks you\u2019re trying to update a file that already exists, but the version you\u2019re putting up is older, that will often result in a 409 error. This may also happen when you\u2019re trying to rename a file, create a directory, and in similar situations. In most cases, you can sidestep the problem by modifying the type of HTTP request that your client makes to the server.<\/p>\n 410 error codes are mostly intended for Search Engine Optimization (SEO) purposes. What this code tells you is that the resource you\u2019re trying to access is gone, and it\u2019s probably not coming back.<\/p>\n From the perspective of an end user, the 404 and 410 error codes might as well be the same thing. They both tell you that the resource you\u2019re looking for isn\u2019t there. However, code 410 also lets search engines know that they shouldn\u2019t continue to crawl and list that page.<\/p>\n This is another example of a highly-specific 400 error code. The 411 Length Required<\/em> error appears when a client makes a request without indicating the length of its content.<\/p>\n Usually, you won\u2019t run into this error while browsing the web. Instead, the 411 Length Required<\/em> error tends to pop up when you\u2019re making a request header through an API. To solve it, you may need to modify the request method itself.<\/p>\n In some cases, when your client makes a request to a server, that request can come with some conditions attached. For example, the request might include an If-Unmodified-Since<\/em> header, and if the server can\u2019t fulfill the criteria, you\u2019ll see the 412 Precondition Failed<\/em> message.<\/p>\n This is another example of a client error that most people don\u2019t encounter while simply browsing the web. If you\u2019re working with an API or something similar, you might need to modify your request so the server can meet its preconditions.<\/p>\n When your client makes a request to a server, it receives data in return. However, there\u2019s a limit to the amount of data that any given server can process at one time.<\/p>\n If you see this error, it means the server can\u2019t or won\u2019t process your request, because it involves too much information. The request itself will need to be simplified if it\u2019s going to work properly.<\/p>\n First, it\u2019s important to understand that a Uniform Resource Identifier (URI)<\/a> isn\u2019t the same as a URL. To put it another way, all URLs are URIs, but not all URIs are URLs.<\/p>\n Semantics aside, the 414 Request-URI Too Long<\/em> error usually occurs when an URL is too long for a simple GET request. In these cases, you\u2019ll need to submit a POST request<\/a> instead.<\/p>\n As far as 400 error codes go, this one is fairly straightforward. Not all servers support every file type. This means that, in some cases, you might try to upload a file only for the end server to reject it. This will trigger the 415 Unsupported Media Type<\/em> error.<\/p>\n To sidestep this problem, you can try to upload the file in a type the server does support. If that\u2019s not possible, you\u2019ll need to change your server\u2019s configuration so that it supports the file types<\/a> you require.<\/p>\n In some cases, a client will make a request for a specific portion of a file, which is referred to as a \u2018range\u2019. If that range exists, the server should return it promptly. However, if there\u2019s an error in the request (for example, if it\u2019s asking for part of a file that doesn\u2019t exist) the server will return the 416 Requested Range Not Satisfiable<\/em> error instead.<\/p>\n This is another example of an internal server error you might run into while working with an API or making highly specific requests to a server. To solve it, all you have to do is modify the range of your request, so the server can fulfill it.<\/p>\n With HTTP, you can check to see if a server can accept your request before you send it. To do that, you\u2019ll use something called an Expect<\/em> header<\/a>. If the origin server can\u2019t accept your request, it will respond with a 417 Expectation Failed<\/em> error message.<\/p>\n In practice, there are several reasons a server might refuse a request. For example, it might be an issue with proxies or with your client\u2019s permissions. In any case, we recommend clearing your cache and cookies, before trying to connect to the server again.<\/p>\nHTTP 400 Bad Request Error<\/h3>\n
HTTP 401 Unauthorized<\/h3>\n
HTTP 402 Payment Request<\/h3>\n
HTTP 403 Forbidden<\/h3>\n
HTTP 404 Not Found<\/h3>\n
HTTP 405 Method Not Allowed<\/h3>\n
HTTP 406 Not Acceptable<\/h3>\n
HTTP 407 Proxy Authentication Required<\/h3>\n
HTTP 408 Request Timeout<\/h3>\n
HTTP 409 Conflict<\/h3>\n
HTTP 410 Gone<\/h3>\n
HTTP 411 Length Required<\/h3>\n
HTTP 412 Precondition Failed<\/h3>\n
HTTP 413 Payload Too Large<\/h3>\n
HTTP 414 Request-URI Too Long<\/h3>\n
HTTP 415 Unsupported Media Type<\/h3>\n
HTTP 416 Requested Range Not Satisfiable<\/h3>\n
HTTP 417 Expectation Failed<\/h3>\n
HTTP 429 TOO MANY REQUESTS<\/b><\/h3>\n