This is the error I get on a fresh Ubuntu Server 14.04 install.
A PHP Error was encountered
Severity: Warning
Message: file_exists(): Unable to find the wrapper "sftp" - did you forget to enable it when you configured PHP?
Filename: libraries/Template.php
Line Number: 2610
I tried to install and enable the ssh2 extension without results! I was sure that this would solve the issue, until I found out that I was trying to access the local file via sftp://srv/.. rather than just /srv/.. (ouch!)
Thanks for all your help!