My checkout suddenly goes to a white page, it never used to do this!

The error I am getting is

Call to undefined function mcrypt_module_open() in /var/www/vhosts/mywebsite.co.uk/httpdocs/lib/Varien/Crypt/Mcrypt.php on line 63

PLEASE HELP! Thank you very much

2 Answers 2


This could be caused by a recent upgrade to PHP and you are missing PHP Mcrypt module.

To install it's usually a simple apt-get install php5-mcrypt on Ubuntu/Debian. A Google search should turn up the correct instructions for your PHP and OS version.


  • Thanks so much for your reply, is there a command I can install this with on Ubuntu server 12? Sep 15, 2014 at 15:23
  • See my updated answer
    – philwinkle
    Sep 15, 2014 at 15:31
  • i have face same issue in few days ago. its php5-mcrypt missing issue
    – Amit Bera
    Sep 15, 2014 at 17:43
  • 7
    TIL you may need to run php5enmod mcrypt on some systems after installing mcrypt via the system's package manager.
    – kojiro
    Nov 18, 2014 at 0:18
  • If apt-get install php5-mcrypt doesn't work, you can try apt-get install php53-mcrypt. Oct 13, 2015 at 23:17

In most of the cases, this issue comes in php updated version i.e. php7 and if mcrypt is not installed -

to install it, follow the below steps:

sudo apt-get update
sudo apt-get install mcrypt php7.0-mcrypt
sudo apt-get upgrade
sudo service apache2 restart
  • My current version of the PHP is 7.2.3, So i followed the command sudo apt-get install mcrypt php7.2-mcrypt, but the package is not found error am getting
    – senthil
    Jan 14, 2021 at 7:29

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