Microsoft has successfully addressed a significant issue affecting certain Microsoft 365 users’ Outlook desktop clients, causing connectivity disruptions to email servers via Exchange ActiveSync. This problem specifically impacted users who had updated their clients to Version 2401 Build 17231.20182. The known issue has been resolved in the latest update, Version 2402 Build 17328.20068, and Microsoft recommends affected users to install the update promptly by navigating to “Update Now” under File > Office Account > Update Options.
Prior to the resolution, Microsoft provided a temporary fix for impacted users, suggesting a rollback of Office M365 Click-to-Run installations to an unaffected build (specifically Version 2312 Build 17126.20132) or switching to an Office Channel without the synchronization issue. Users who had applied the temporary fix were instructed to re-enable updates by selecting File > Office Account > Update Options > Enable Updates. Microsoft is actively investigating another issue related to Outlook, which triggers security alerts when attempting to open .ICS calendar files after installing December 2023 Patch Tuesday Office security updates.
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