Got the following error trying to upgrade:
Undefined index: datatable_archiving_maximum_rows_referrers
in ‘/home/mysite/public_html/mysite/piwik/core/Config/Compat.php’ at the line 52
#0 Piwik_ErrorHandler(…) called at [/home/mysite/public_html/mysite/piwik/core/Config/Compat.php:52]
#1 Piwik_Config_Compat_Array->__get(…) called at [/home/mysite/public_html/mysite/piwik/plugins/EntryPage/EntryPage.php:41]
#2 Piwik_EntryPage->__construct(…) called at [/home/mysite/public_html/mysite/piwik/core/PluginsManager.php:391]
#3 Piwik_PluginsManager->loadPlugin(…) called at [/home/mysite/public_html/mysite/piwik/core/PluginsManager.php:343]
#4 Piwik_PluginsManager->reloadPlugins(…) called at [/home/mysite/public_html/mysite/piwik/core/PluginsManager.php:235]
#5 Piwik_PluginsManager->loadPlugins(…) called at [/home/mysite/public_html/mysite/piwik/core/FrontController.php:278]
#6 Piwik_FrontController->init(…) called at [/home/mysite/public_html/mysite/piwik/index.php:52]