The WordPress error 404 means HTTP 404 which shows the Not Found response status code. This code indicates that the server is unable to find the requested resource. The main cause of his error is the Links that lead to a 404 page are usually called broken or dead links and can be subject to link rot. If you want to fix this then try

1. Retry the web page by pressing the key F5. Another way that you can try is to refresh by refresh/reload button or clicking/tapping, or you can try the URL from the address bar multiple times..
2. Check for errors in the URL.
3. Change the directory level at a time in the URL until you find something.