There are two different models: product.management and  process.management in module A and module B respectively.

In process.management, it has a Many2one field:

product_id = fields.Many2one('product.management', 'product')

In product.management, it has a One2many field:

process_ids = fields.One2many('process.management', 'product_id', 'process')

and then the error came out.

Any help would be appreciated!