YOU MUST UPDATE THE PROFESSIONAL VERSION MANUALLY. Due to the changes in the packaging format and the way Joomla's extensions updater works the Download ID of the Professional release was not registered with Joomla. As a result any attempt to update Admin Tools from 4.0.0.b1, 4.0.0.b2, 4.0.0.rc1 or 4.0.0 to this version using the Joomla extensions updater will NOT work. You MUST download this new version and install it on your site like any other extension. This will address the update issue.
Several issues regarding passwords with non-alphanumeric characters were addressed in this release. These issues primarily affected the Master password and Administrator Password Protection features.
Updating from Admin Tools 3.5 or earlier could cause a PHP Fatal error due to a leftover file.
This version of Admin Tools will only work on Joomla 3.4 and later versions, including the brand new Joomla 3.6.
We VERY STRONGLY advise you to update to the latest released version of Joomla! at all times. Admin Tools' support for older versions of Joomla! is only meant to be a temporary workaround while you're working on the update of your site.
Please note that we will only provide full support for the latest Joomla! version. Some features may not work at all in older Joomla! versions. We've thoroughly tested the security critical Web Application Firewall features against the supported versions of Joomla! as stated above and found them to be working properly.
Support for PHP 5.3 is discontinued. It's end of life since August 2014 and widely considered a security risk, unfit for production sites. Our software requires PHP 5.4 or later and is compatible with PHP 5.4, 5.5, 5.6 and 7.0. We strongly recommend using PHP 5.6 or 7.0.
We'd like to remind you that Joomla! 3.4 does NOT support PHP 7. PHP 7 is only supported by Joomla! 3.5.0 and later versions. Admin Tools will work perfectly fine (and very fast!) on a Joomla! 3.6 or later site running on PHP 7.0.