As described on previous post, plugin Autosize had too many problems. Anyway the feature of automatic photo size is an excellent one. Plugin Automatic Size is taking over, with a much simpler code (simpler code = less bug).
Plugin Automatic Size is now available for Piwigo 2.4 and 2.5 on Piwigo.com. Considering many users are still blocked on Piwigo 2.4 because they use Autosize, in the coming days we will change the upgrade script for accounts: if Autosize is activated, it will automatically be deactivated and Automatic Size will be activated. This will allow the upgrade to version 2.5.