I am using Magento 1, installed on a Windows 10 php(7.2) WampServer.
I tried to add this extension=php_mcrypt.dll in php.ini, but continued to receive the error.
How to add extension=php_mcrypt.dll in Windows 10 to resolve this error?
After installed extension=php_mcrypt.dll, have you restarted the Apache? If not please do it, then check.
Or you can follow these steps.