The workaround is not to try accessing Calendar from the affected devices. If a user runs into the problem, rebooting the device may clear it up, Microsoft says. If not three other options might work: remove the Exchange account from the Apple device, wait half an hour and reinstall it; throttle the number of iOS devices that can access the server at the same time; and block all iOS devices from the server.
The second option will help protect server performance, but won't prevent the error messages, Microsoft says.
The support notification also advises how to detect whether the problem exists in a particular network.
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