This was the error message I got in PhpMyadmin in Ubuntu 14.04-2.
The mcrypt extension is missing. Please check your PHP configuration.
So I found the following solution in:
http://askubuntu.com/questions/460837/mcrypt-extension-is-missing-in-14-04-server-for-mysql/477608#477608

First, I’m not really sure that this directory needs to be created, but since it’s in php.ini configuration, I’d rather make sure all will work fine.
Extract of php.ini
................
[mcrypt]
; For more information about mcrypt settings see http://php.net/mcrypt-module-open
;
; Directory where to load mcrypt algorithms
; Default: Compiled in into libmcrypt (usually /usr/local/lib/libmcrypt)
;mcrypt.algorithms_dir=
;
; Directory where to load mcrypt modes
; Default: Compiled in into libmcrypt (usually /usr/local/lib/libmcrypt)
;mcrypt.modes_dir=
.................

Therefore create the directory and set its ownership:
mkdir /usr/local/lib/libmcrypt
chown www-data: /usr/local/lib/libmcrypt

Install the PHP mcrypt module.
apt-get install mcrypt php5-mcrypt
php5enmod mcrypt
service apache2 restart