Memcached - "No Memcached servers added" after upgrading to ubuntu 16.04

Does upgrading from ubuntu 14.04 to 16.04 affect multi-server memcached?

I have a Laravel 5.1 application which utilizes memcached to manage sessions across multiple servers, specifically two web servers and a database server.

After upgrading the OS on each server from ubuntu 14.04 to 16.04 and installing the latest version of mariadb (10.1.*), our laravel application now returns the following error:

[RuntimeException] No Memcached servers added.

My config files have not changed and neither have the ip addresses of any of the servers. Debugging laravel's MemcachedConnector.phpshows the server details being passed to the Memcached class but the output of Memcached::getVersion() returns false.

I am at a loss as to why this has suddenly stopped working, any assitance would be appreciated.

via Chebli Mohamed