Resolved in KB5128895Known issue · Exchange Server update known issues · Exchange
Published calendar (.ics) returns HTTP 500 for calendar applications
After you install the August 2026 security update (Exchange Server SE, build 15.2.2562.46), subscriptions to an anonymously published Exchange calendar stop refreshing. The subscribing application reports a server error, and the URL returns HTTP 500.
36
Days since it was published · 8 Sep 2026
Other open issues in Exchange
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- Availability (free/busy) fails for delegated mailboxes in Exchange hybrid deployments using Graph API onlyOpen · Exchange Server update known issues
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What changed
First observed 14 Oct 2026No field changes in the recorded history.
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