RESTAPINotEnabledForComponentSharedMailbox error

Question

I have users that cannot use our services because Outlook REST API returns the following error code RESTAPINotEnabledForComponentSharedMailbox.

It looks like their mailbox is not a shared mailbox. So what kind of mailbox is that?

Can you tell me more about this error? Is there something we can do?

Answer 1

This means user doesn't have their mailbox in O365 cloud. This can mean that their mailbox is either on premises or they don't even have any mailbox. You should use auto discover to get the right end point to connect.