If you have migrated from Blogger to WordPress or any other php site, what ever the case might be. You are probably stuck with back links that doesn’t work since they point to a 404 page.

In wordpress, there is a very handy plugin called Redirection. This allows to redirect all your pages that ends with .html to your newly pages. (same names)

Simply navigate to Tools>Redirection>modules.

Add a new/existing .htaccess file, and set to remove trailing .html.

That is it. Good luck