I can not send messages nor add followers in my opportunities

Traceback (most recent call last):

  File "/opt/sc/odoo/odoo/odoo/http.py", line 638, in _handle_exception return super(JsonRequest, self)._handle_exception(exception) File "/opt/sc/odoo/odoo/odoo/http.py", line 675, in dispatch result = self._call_function(**self.params) File "/opt/sc/odoo/odoo/odoo/http.py", line 331, in _call_function return checked_call(self.db, *args, **kwargs) File "/opt/sc/odoo/odoo/odoo/service/model.py", line 119, in wrapper return f(dbname, *args, **kwargs) File "/opt/sc/odoo/odoo/odoo/http.py", line 324, in checked_call result = self.endpoint(*a, **kw) File "/opt/sc/odoo/odoo/odoo/http.py", line 933, in __call__ return self.method(*args, **kw) File "/opt/sc/odoo/odoo/odoo/http.py", line 504, in response_wrap response = f(*args, **kw) File "/opt/sc/odoo/odoo/addons/web/controllers/main.py", line 866, in call_button action = self._call_kw(model, method, args, {}) File "/opt/sc/odoo/odoo/addons/web/controllers/main.py", line 854, in _call_kw return call_kw(request.env[model], method, args, kwargs) File "/opt/sc/odoo/odoo/odoo/api.py", line 681, in call_kw return call_kw_multi(method, model, args, kwargs) File "/opt/sc/odoo/odoo/odoo/api.py", line 672, in call_kw_multi result = method(recs, *args, **kwargs) File "/opt/sc/odoo/odoo/addons/mail/wizard/invite.py", line 63, in add_followers new_partners.with_context(auto_delete=True)._notify(message, force_send=True, send_after_commit=False, user_signature=True) File "/opt/sc/odoo/odoo/addons/mail/models/res_partner.py", line 156, in _notify ('notify_email', '!=', 'none')])._notify_by_email(message, force_send=force_send, send_after_commit=send_after_commit, user_signature=user_signature) File "/opt/sc/odoo/odoo/addons/mail/models/res_partner.py", line 201, in _notify_by_email new_emails, new_recipients_nbr = self._notify_send(fol_values['body'], fol_values['subject'], recipient_template_values['followers'], **base_mail_values)KeyError: 'body'