Hi,

Here in your code, one of the variable is getting the value as False, that is why you are getting this error message, so add some print statements in the code and see which one is causing the problem, and rectify it by giving the IF condition.

If you are looking to create sequence for your model, better to follow the standard way of using the ir.sequence, see the sample below,

In XML,

<odoo>
    <data noupdate="1">

        <!-- ------*.xml file------- -->
        <record id="seq_hr_employee" model="ir.sequence">
            <field name="name">omega_sequencer</field>
            <field name="code">hr.employee</field>
            <field name="prefix">QO</field>
            <field name="padding">5</field>
        </record>

    </data>
</odoo>

Then in the Python,

# ------------*.py file------------------
class omega(models.Model):
    _name = 'omega.model'
    _description = 'No Description for now !!'

    sequence_id = fields.Char('Sequence', readonly=True)

    @api.model
    def create(self, vals):
        seq = self.env['ir.sequence'].next_by_code('hr.employee') or '/'
        vals['sequence_id'] = seq
        return super(omega, self).create(vals)

See the link: Create a sequence number

Thanks