I have installed Php 7.1.9 on a windows server 2012 machine, if I check the php info I can see that mcrypt is enabled but if I type in shell php -v I have this error:
Unable to load dynamic library 'C:/php/ext\php_mcrypt.dll' - The specified module could not be found.
In fact running a Laravel application I also get some exception related to it.
I have checked ext folder and there is no php_mcrypt.dll .
As you can see here mcrypt is deprecated in favour of OpenSSL. From the Deprecated features in PHP 7.1.x: