Fatal error: t3import not found object: core.libs.browser in /home/website/public_html/plugins/system/jat3/jat3/core/common.php on line 33

After updating a local copy of 2.5 (Joomla core and all extensions and plugins) then reloading a backup site, error appears on the frontend (backend is accessible and working):
Fatal error: t3import not found object: core.libs.browser in /home/website/public_html/plugins/system/jat3/jat3/core/common.php on line 33

Fix: Upgraded to latest JA T3v2 System Plugin for J25 & J30
Extensions > Install > upload and install latest downloaded JA T3 plugin (no need to uninstall previous version, install overwrite works). For some reasons, plugin got messed up through the backup and reloading process, thus a fresh installation from the backend is needed.