diff --git a/addons/google_calendar/models/calendar.py b/addons/google_calendar/models/calendar.py
index 370ddc261a4..969c5873537 100644
--- a/addons/google_calendar/models/calendar.py
+++ b/addons/google_calendar/models/calendar.py
@@ -224,7 +224,10 @@ class Meeting(models.Model):
         if self.user_id and self.user_id != self.env.user and bool(self.user_id.sudo().google_calendar_token):
             # We avoid updating the other attendee status if we are not the organizer
             attendees = self.attendee_ids.filtered(lambda att: att.partner_id == self.env.user.partner_id)
-        attendee_values = [{'email': attendee.partner_id.email_normalized, 'responseStatus': attendee.state} for attendee in attendees if attendee.partner_id.email_normalized]
+        attendee_values = [{
+            'email': attendee.partner_id.email_normalized,
+            'responseStatus': attendee.state or 'needsAction',
+        } for attendee in attendees if attendee.partner_id.email_normalized]
         # We sort the attendees to avoid undeterministic test fails. It's not mandatory for Google.
         attendee_values.sort(key=lambda k: k['email'])
         values = {
diff --git a/addons/google_calendar/tests/test_sync_odoo2google.py b/addons/google_calendar/tests/test_sync_odoo2google.py
index 539c6ab7c60..df39feefaad 100644
--- a/addons/google_calendar/tests/test_sync_odoo2google.py
+++ b/addons/google_calendar/tests/test_sync_odoo2google.py
@@ -134,6 +134,40 @@ class TestSyncOdoo2Google(TestSyncGoogle):
         values = event._google_values()
         self.assertFalse('%s_owner_id' % self.env.cr.dbname in values.get('extendedProperties', {}).get('shared', {}))
 
+    @patch_api
+    def test_event_without_attendee_state(self):
+        partner_1 = self.env['res.partner'].create({'name': 'Jean-Luc', 'email': 'jean-luc@opoo.com'})
+        partner_2 = self.env['res.partner'].create({'name': 'Phineas', 'email': 'phineas@opoo.com'})
+        partner_3 = self.env['res.partner'].create({'name': 'Ferb'})
+        event = self.env['calendar.event'].create({
+            'name': "Event",
+            'start': datetime(2020, 1, 15, 8, 0),
+            'stop': datetime(2020, 1, 15, 18, 0),
+            'partner_ids': [(4, partner_1.id), (4, partner_2.id), (4, partner_3.id)],
+            'privacy': 'private',
+            'need_sync': False,
+        })
+        attendee_2 = event.attendee_ids.filtered(lambda a: a.partner_id.id == partner_2.id)
+        attendee_2.write({
+            'state': False,
+        })
+        event._sync_odoo2google(self.google_service)
+        self.assertGoogleEventInserted({
+            'id': False,
+            'start': {'dateTime': '2020-01-15T08:00:00+00:00'},
+            'end': {'dateTime': '2020-01-15T18:00:00+00:00'},
+            'summary': 'Event',
+            'description': '',
+            'location': '',
+            'visibility': 'private',
+            'guestsCanModify': True,
+            'reminders': {'useDefault': False, 'overrides': []},
+            'organizer': {'email': 'odoobot@example.com', 'self': True},
+            'attendees': [{'email': 'jean-luc@opoo.com', 'responseStatus': 'needsAction'},
+                          {'email': 'phineas@opoo.com', 'responseStatus': 'needsAction'}],
+            'extendedProperties': {'shared': {'%s_odoo_id' % self.env.cr.dbname: event.id}}
+        })
+
     @patch_api
     def test_event_allday_creation(self):
         event = self.env['calendar.event'].create({