NOTE - Even though the web pages produce an error, the device itself should have been created, although with no data in the associated "ip" table.
You may wish to delete any created devices device and recreate.
There is a bug in the file:
Linux - /usr/local/open-audit/code_igniter/application/controllers/devices.php
Windows - c:\xampplite\open-audit\code_igniter\application\controllers\devices.php
In 2.3.1, delete the lines 235, 236, 237.
In 2.3.2, delete lines are 252, 253, 254.
Insert the below (from line 235 or 252, per version above).