404 Redirect occurs when a customer on your site tries to access a pagename that doesn’t exist. These are dead pages that link nowhere and gives users a bad experience. If these pages remain unfixed, Google will de-index these pages and all the valuable links, rank, SEO juice, and authority attributed to these pages will be wasted. 404 Error pages that are not redirected will annoy users and make them leave your site immediately
The http error 403 is an error message that is occasionally displayed in the user’s web browser. The 403 error is one of the many hypertext transfer protocol responses that can appear when attempting to access a web page. If the ‘403 Forbidden’ message appears in your browser instead of the website you requested, it means that you are not authorized to access the specified URL.