Create custom error pages through .htaccess file

1. 404 - page not found

 RewriteEngine On
 ErrorDocument 404 /404.html

2. 500 - Internal Server Error

RewriteEngine On
ErrorDocument 500 /500.html

3. 403 - Forbidden

RewriteEngine On
ErrorDocument 403 /403.html

4. 400 - Bad request

RewriteEngine On
ErrorDocument 400 /400.html

5. 401 - Authorization Required

RewriteEngine On
ErrorDocument 401 /401.html

You can also redirect all error to single page. like

RewriteEngine On
ErrorDocument 404 /404.html
ErrorDocument 500 /404.html
ErrorDocument 403 /404.html
ErrorDocument 400 /404.html
ErrorDocument 401 /401.html