HTTP Status codes are basically the conversion between the web browser and the website's server. In most cases, you as a user won't be able to see the HTTP status codes unless and until there is an issue. In case of issue HTTP status codes are used as a way of communicating errors to the user.
Error messages or we can say HTTP codes are displayed when your internet browser is unable to reach the page requested by a user.
What is a 4xx Response?
This group of HTTP status codes indicates that the request for the resource contains bad syntax or cannot be filled for some other reason, presumably by the fault of the client sending the request. Except when responding to a HEAD request, the server SHOULD include an explanation of the error situation and whether it is a temporary or permanent condition. These status codes are applicable to any request method.
What do 4xx Response Look Like?
4XX status codes are shown when the client requests a page that cannot be accessed. This is usually the result of a bad or broken link. These statuses are the most common requests an SEO will encounter – the 400, 403 and 404 errors. These errors simply mean that the resource is unavailable and unable to load. For instance, you may encounter 401 response code like this:
Guide to 4xx Response Codes-
There are a number of different 4xx server Responses, numbered with their own response codes so that the problem can be identified.
Some of the most common HTTP 4xx Response codes are listed below:
Internet Information Services
AWS Elastic Load Balancer
Since user error is often what triggers a 4xx status code, we have consolidated a list of things you can do to remedy the situation if it happens to you. For all status codes listed above, if the listed solutions don't work, clear the cache and cookies to make sure those aren't causing the error.