How to properly redirect from .php to a page without .php?

Question

1C-Bitrix

The bottom line is that the Redirect 301 /mezhkomnatnye-dveri/avangard.php /catalog/interior-doors/avangard/ redirect is set in .htaccess As a result, the redirect to
the page /catalog/interior-doors/avangard.php is not quite correct
on /catalog/interior-doors/avangard/
Maybe I googled badly, but unfortunately I didn’t find anything similar.
Tell me how to do it right.

Answer 1

You are correct - as you need - redirect to the page /catalog/interior-doors/avangard/.
But as I understand it, /catalog/interior-doors/avangard.php opens?
Well, this is not because your redirect is not correct, but because somewhere else there is a redirect to /catalog/interior-doors/avangard.php
Look carefully.
To check if it is Bitrix itself, you can temporarily
delete everything in the /catalog/interior-doors/avangard/index.php file. If you stop redirecting to /catalog/interior-doors/avangard.php, then the redirect is somewhere in PHP. If you continue - redirect somewhere in the server settings.