SEO 404 error
The 404 error is the most common HTTP error that users often encounter while browsing the web. It is an HTTP standard response code which indicates that client is able to contact the server but the server is not able to find the page requested by the client. Thus, it simply means that the webpage you are trying to reach cannot be found on the server.
404 error usually arises due to a wrong link on your site or if you have removed the requested page. It usually occurs when a redirect to the new URL has not been implemented. If you don't create 404 Error Page, it can affect your SEO. It is required to have 404 error page because it is a common problem. To create a 404 page, you need to redirect all irrelevant requests to a single 404 error page.
You can do few things to make the 404 user-experience better, such as: