HTTP 404 Error When the client browses the web page using HTTP, the server cannot find the specified resource or the requested file does not exist; Explain that the web page pointed by the link does not exist, that is, the URL of the original web page is invalid. When the Web server receives a similar request, it will return an http 404 status code, telling the browser that the requested resource does not exist.

The purpose of the 404 page is to tell the viewer that the requested page does not exist or the link is wrong, and at the same time guide the user to use the website to shape other pages instead of closing the window and leaving.

Second, why is there an http 404 error?

The change of pseudo static rule makes the URL of web page change.

The web page file or site directory has been moved or its name has been changed.

Spelling error of anchor text import link outside the station

Caused by database error or program error.

Server configuration errors and other server problems.

The user misspelled the domain name or web address.

Third, the impact of http 404 errors on SEO.

As SEOer, we should avoid dead links, because the number of dead links can evaluate the authority of a website.

Customizing 404 error pages is a good way to provide user experience, but the impact on search engines in the application process is often ignored, such as the return of "200" status code due to wrong server-side configuration or the return of "302" status code due to the use of Meta refresh in customizing 404 error pages. A properly set custom 404 error page should not only be displayed correctly, but also return a "404" error code instead of "200" or "302". Although it makes no difference whether the HTTP status code is "404" or "200" for visiting users, it is quite important for search engines.

When the search engine spider gets a "404" status response when requesting a URL, it knows that the URL is invalid, so it stops indexing the webpage and feeds it back to the data center to delete the webpage represented by the URL from the index database. Of course, the deletion process may take a long time. When the search engine obtains the "200" status code, it will think that the url is valid, and it will be indexed and included in the index database. In this way, the contents of these two different URLs are exactly the same: customizing the contents of the 404 error page will lead to the problem of copying the web page. Light ones will be downgraded by search engines, and heavy ones will drop websites.

If you decide to update the page layout, our page layout algorithm will automatically reflect the layout change when it is re-crawled, and process enough pages to evaluate this change. The time required for this process depends on many factors, including the number of pages on the website and the efficiency of Googlebot in capturing the content of the website. For an ordinary website, it may take several weeks for Googlebot to grab and process enough pages to reflect the change of website layout.