I've seen multiple tickets with this same error, but I thought i'd share the error messages I got:
I updated admintools pro to version 3.2.1 and my front & back-end went blank, I enabled error reporting by modifying the configuration.php using FTP and I got the following errors:
Fatal error: Call to a member function getQuery() on a non-object in /home/irepair/domains/irepaircuracao.com/public_html/plugins/system/admintools/feature/autoipfiltering.php on line 24
so I renamed autoipfiltering.php to autoipfiltering.php.bak and refreshed the page and got the following error:
Fatal error: Call to a member function getQuery() on a non-object in /home/irepair/domains/irepaircuracao.com/public_html/plugins/system/admintools/feature/deleteinactive.php on line 41
I then renamed deleteinactive.php to deleteinactive.php.bak as well and then the front & back end seemed to work again, after which I reinstalled admin tools professional 3.2.0
I was able to reproduce the same problem on another joomla 2.5.26 site, on joomla 3.3.6 the update seems to work.
Hope to have provided some useful information :)
Regards,
Carl