Automatic redirect pages without .html

All my pages was redirect to the same pages but without the .html is it possible to avoid that ?

In the browser this is transparent but all the pages of my site give a 308 because all links was on .html and when you get headers with postman (for example), the location header is not correctly encoded (accent give a wrong char) and auto follow redict was broken.

Thanks for your help

Please, some solution to avoid this. Thank you