Hi, I have an odoo 10 installation where I put the unique constraint on the default code, so far everything worked correctly but after moving the installation to a new server when I try to create a new code by the create and edit menù (for example in a sales order line) even if the code does not exist, it returns this error. The key (default_code) = () already exists. Also if I try to insert a new code that does not exist by clicking on create I will open the window create product and I will not have it created immediately.

What can I check to understand how to solve the problem?