Hi,
I just updated piwik from 1.8.3 to 1.8.4 and got this message. AFAIK everything is fine although.
There is an error. Please report the message (Piwik 1.8.4) and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).
Warning: Invalid argument supplied for foreach() in /var/www/piwik/core/Config.php on line 440
Backtrace -->
#0 Piwik_ErrorHandler(…) called at [/var/www/piwik/core/Config.php:440]#1 Piwik_Config->dumpConfig(…) called at [/var/www/piwik/core/Config.php:495]#2 Piwik_Config->writeConfig(…) called at [/var/www/piwik/core/Config.php:509]#3 Piwik_Config->forceSave(…) called at [/var/www/piwik/core/Updates.php:68]#4 Piwik_Updates::enableMaintenanceMode(…) called at [/var/www/piwik/core/Updates/1.8.4-b1.php:178]#5 Piwik_Updates_1_8_4_b1::update(…) called at [:]#6 call_user_func(…) called at [/var/www/piwik/core/Updater.php:172]#7 Piwik_Updater->update(…) called at [/var/www/piwik/plugins/CoreUpdater/Controller.php:367]#8 Piwik_CoreUpdater_Controller->loadAndExecuteUpdateFiles(…) called at [/var/www/piwik/plugins/CoreUpdater/Controller.php:348]#9 Piwik_CoreUpdater_Controller->doExecuteUpdates(…) called at [/var/www/piwik/plugins/CoreUpdater/Controller.php:270]#10 Piwik_CoreUpdater_Controller->runUpdaterAndExit(…) called at [/var/www/piwik/plugins/CoreUpdater/Controller.php:237]#11 Piwik_CoreUpdater_Controller->index(…) called at [:]#12 call_user_func_array(…) called at [/var/www/piwik/core/FrontController.php:138]#13 Piwik_FrontController->dispatch(…) called at [/var/www/piwik/index.php:53]