While sending meeting invites on iPhone, the error message pops up as:
Calendar Invitation - Your response to the invitation cannot be sent.
The error is generated by the 'My Exchange' account.
Turn off iCloud Contacts, Calendar, or Reminders and turn it back on.
- Tap Settings > [your name] > iCloud. (If you're using iOS 10.2 or earlier, go to Settings > iCloud.)
- Slide to turn off Contacts, Calendars, and Reminders.
- If you see your calendars or reminders on iCloud.com or any of your devices, you can choose Delete from My [device]. If not, choose Keep on My [device].
- Wait a few minutes, then turn on Contacts, Calendar, or Reminders again.