diff --git a/addons/calendar/models/calendar.py b/addons/calendar/models/calendar.py
index 471de145472..b547a2fbe3a 100644
--- a/addons/calendar/models/calendar.py
+++ b/addons/calendar/models/calendar.py
@@ -897,13 +897,16 @@ class Meeting(models.Model):
                 enddate = tz.localize(enddate)
                 enddate = enddate.replace(hour=18)
                 enddate = enddate.astimezone(pytz.utc)
-                meeting.stop = enddate
 
                 startdate = fields.Datetime.from_string(meeting.start_date)
                 startdate = tz.localize(startdate)  # Add "+hh:mm" timezone
                 startdate = startdate.replace(hour=8)  # Set 8 AM in localtime
                 startdate = startdate.astimezone(pytz.utc)  # Convert to UTC
-                meeting.start = startdate
+
+                meeting.write({
+                    'start': startdate.replace(tzinfo=None),
+                    'stop': enddate.replace(tzinfo=None)
+                })
             else:
                 meeting.write({'start': meeting.start_datetime,
                                'stop': meeting.stop_datetime})
diff --git a/odoo/fields.py b/odoo/fields.py
index 16a58d70653..650eaebb799 100644
--- a/odoo/fields.py
+++ b/odoo/fields.py
@@ -1681,6 +1681,8 @@ class Datetime(Field):
             return None
         if isinstance(value, date):
             if isinstance(value, datetime):
+                if value.tzinfo:
+                    raise ValueError("Datetime field expects a naive datetime: %s" % value)
                 return value
             return datetime.combine(value, time.min)
         try: