Extending an all-day event on a shared calendar unexpectedly shortens or lengthens the event

Last Updated: February 13, 2023

ISSUE

When a delegate with Editor permissions extends an all-day event on a shared calendar, the event will automatically be either shortened or lengthened. If you are in a UTC minus time zone, the event will be shortened by the number of hours you are behind UTC. However, if you are in a UTC plus time zone, the event will be lengthened by the number of hours you are ahead of UTC. The time zone for the event will also display as UTC instead of the original time zone. 

TROUBLESHOOTING​​​​​​​

To verify the issue is present, admins can run a network trace while reproducing the issue.   

They will collect a request from Outlook with the new details about the event where the correct time zone is shown. 

However, the response received by Outlook will contain a different time zone, which will cause the change on the event. 

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STATUS: WORKAROUND

As a workaround, users have the option to disable the Shared Calendar improvements feature for their account. 

The following article contains guidance for how to disable Shared Calendar improvements: How to enable and disable the Outlook calendar sharing updates.