Prestashop website: white screen

My Prestashop 1.6 website shows a blank screen
Debug says: " Deprecated: The each() function is deprecated. This message will be suppressed on further calls in /web/htdocs/www......com/home/tools/smarty/sysplugins/smarty_internal_compilebase.php on line 75
Tried several php version, nothing
Need to fix it as soon as possible