Hi, you can use this code:

class Followers(models.Model):
    _inherit = 'mail.followers'

    @api.model
    def create(self, vals):
        if 'res_model' in vals and 'res_id' in vals and 'partner_id' in vals:
            dups = self.env['mail.followers'].search([('res_model', '=',vals.get('res_model')),
                                               ('res_id', '=', vals.get('res_id')),
                                               ('partner_id', '=', vals.get('partner_id'))])
            if len(dups):
                for p in dups:
                    p.unlink()
        res = super(Followers, self).create(vals)
        return res

Hi Othmane,

You can solve the issue by referring this blog, https://www.cybrosys.com/blog/how-to-get-rid-of-the-error-a-partner-cannot-follow-twice-the-same-object

Thanks

I already see it, I want a general solution for all the models