How I am getting this error.
1. I have leave type Unpaid with double validation selected.
2. I create new leave request for Unpaid leave type and then Confirm.
3. When the manager click on "Approve" getting this error.
Any idea whats wrong.. Following is the error in Odoo 12
> /odoo/fields.py(1966)convert_to_cache() -> raise ValueError("Wrong value for %s: %r" % (self, value))