A couple of weeks ago I updated the site to Joomla 2.5.14 and the Kunena forum extension was upgraded to 3.0.1 at the same time.  Now it was the right time to go even more responsive with the JA Elastica template.  The latest versions were downloaded from Joomlart and the update to version 2.5.3 worked all right, still under Joomla 2.5.  This step made sure that the template was compatible with Joomla 3.  However, after I pushed the button and upgraded to 3.1.5, the following message was displayed both at the back end and the front end:

Fatal error: Class 'JParameter' not found in /home/myaccount/public_html/mysite/plugins/system/bigshotgoogleanalytics/bigshotgoogleanalytics.php on line 24

All the plugin information resides in the extension table in the database.  The system plugin bigshotgoogleanalytics had to be disabled by changing the column `enabled` from 1 to 0 and the site is again online.  The Google Analytics tracking code was then added manually before the <head> tag in the file page/default.php in the ja_elastica template.

The error highlights the importance of checking all the extensions for compatibility during version upgrades.