404 Not Found error messages can appear in any browser and in any operating system. Most 404 Not Found errors display inside the Internet browser window just as webpages do.
Cause of HTTP 404 Errors
A 404 error is an HTTP status code that means that the page you were trying to reach on a website couldn't be found on their server.
Technically, an Error 404 is a client-side error, implying that the error is your mistake, either because you typed the URL in wrong or the page has been moved or removed from the website and you should have known.
Another possibility is if a website has moved a page or resource but did so without redirecting the old URL to the new one. When that happens, you'll receive a 404 error instead of being automatically routed to the new page.
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