The “Button-CommandName” pass-through attribute has a new value called “CustomPostback” used for Crystal Reports buttons added to your application via the Crystal Reports tool box control.
During migration, Crystal Reports buttons you have added to your application may be removed.
You should manually remove any Crystal Reports buttons that are not removed during migration. Then, drag and drop new Crystal Reports buttons from the Iron Speed Designer tool box into your application pages and configure the button controls appropriately.
Version 5.0 Application Migration