When enabling OpenSSL you might get this error message if you use Xampp on Windows. Follow this steps to resolve the problem:
- Stop your Apache.
- In the folder `xamppphp` you will find two DLL: libeay32.dll and ssleay32.dll. Copy them into the folder `xamppapachebin`
- Open the `xamppphpphp.ini` file and remove the semicolon in front of `extension=php_openssl.dll`
- Start you Apache