You should have noticed by now that when you visit a broken link or a link that doesnt exist in blogger’s blog, you would be redirected to a page that reads
“Sorry, the page you were looking for in this blog does not exist.”
Now blogger has given its users the ability to edit or design your 404 error page to you test. Follow this procedures.
To change your 404 Error, simply Log in to your Blogger account. (you must be using
the new Blogger dashboard)
Go to Settings > Search preferences > Custom Page not Found. > Click Edit to open the
text box. Type whatever you would like to appear on the page, then click on “Save
Changes”.
And guess what! HTML code is also allowed.