Doing the metadata refresh, i have always the message incomplete and the following message in the logfile :

WARNING: file_exists(): open_basedir restriction in effect. File(/home/users3/b/zzzzzzz/www/xxxxxxx/categories/vehicules/bateaux.alb/zp-core_images_imageDefault.png) is not within the allowed path(s): (/home/users3/b/baudelet:/home/temporaire/upload:/tmp:/usr/local/lib/php:/usr/local/lib/ZFramework) in /home/users3/b/baudelet/www/lecarnet/zp-core/i.php on line 116

file_exists called from i.php [116]

What is possible todo ?

open basedir is some server security triggering where it shouldn't. Try to contact your host about that.

Thanks acrylian, still wrong permissions, each upgrade change the files and directories permissions...

What are the necessary permissons for the .alb files ?

Those that are recommended on the user guide article. if you set the strictest permission via setup try one level less as those often don't work on (shared) host because they have already security measures active. If only 777 works contact your host as you should never use those.