raise UserError(_("Failed to render template %r using values %r")% (template, variables))

on py file the code is below:

    def follow_up_date_scheduler_queue(self):
        today = fields.Date.context_today(self)
        tomorrow = fields.Date.from_string(today) + timedelta(days=1)
        identities = self.search([('follow_date', '=', tomorrow)])
        # Find the e-mail template
        template = self.env.ref('identity_check.email_template_for_identity_followup')
        for identity in identities:
            self.env['mail.template'].browse(template.id).send_mail(identity.id, force_send=True)
        # return mail_id
        return

On XML file the email template code is below:

<!--Email template-->
        <record id="email_template_for_identity_followup" model="mail.template">
            <field name="name">Send Identity Followup email</field>
            <field name="email_from">${object.user_id.email}</field>
            <field name="subject">Followup for ${object.name}</field>
            <field name="email_to">${object.user_id.email}</field>
            <field name="model_id" ref="base.model_res_partner"/>
            <field name="auto_delete" eval="True"/>
            <field name="lang">${object.lang}</field>
            <field name="body_html"><![CDATA[
                """
                Write here a body of email using HTML tag.....
                """
            ]]></field>
        </record>