You have two options: share from OWA (recommended, also accept share there) or make sure you select the sharee from the GAL, not from autocomplete. More info at
Outlook error: 'error preparing to send sharing message'
Thanks again Diane, you have helped me in the past.
When I try to select the sharee from the Global Addess List by clicking the "To" button, The GAL window pops up, is empty, and an error message box also pops up saying"The requested operation cannot be completed because the operation is not supported on this object". On the Address Book drop down menu I have the choice of GAL (Empty), My email address (Empty), and Contacts (Fully populated) but does not work (original error of this post). I looked at the MFCMapi stuff and could follow the steps I believe, but don't want to screw up and lose anything/everything. I don't know what "Delegates" are if I am able to delete them as shown, and would not have a clue on how to re-add any if I have to. The only reason for not wanting to to do the OWA (which works) is that my wife was fed up with getting
two emails of changes or additions to the calendar and they would re-appear all the time after deletion day after day (another subject). She just needs to see the calendar occasionally when desired. So I had removed all sharing and wanted a fresh start from Outlook. It was a simple plan

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