Knowledgebase
How to change the Magento 404 Page Not Found page
The default 404 error page in Magento is called 404 Not Found 1 and can be edited from the Magento admin panel > CMS > Pages > 404 Not Found 1.
If you want to create a new 404 error page, go to CMS > Pages, click Add New Page and create your new page.
Then you can easily change the Magento 404 Page Not Found page from the admin panel > System > Configuration > Web > Default Pages.
From the CMS No Route Page drop-down menu select the new page you want to use as a default 404 error page and click Save Config to save the change.