Usually when a 404 error is encountered on a blogger blog, your visitor get a message like “Sorry, the page you were looking for in this blog does not exist”
but, this is of no use for the visitor and most of them leave the page, to avoid this you can create and customize your “404 Page not found” Error Page. Just add a search bar and give some links and there is more chance that your visitor remains in your site.
1. Go to your blogger dashboard and choose your blog
2. Go to Settings -> Search Preferences -> Errors and Redirection -> Custom Page Not Found
3. Copy and paste the below code into the box and save changes