Microsoft Resolves Outlook Sync Issue Over Exchange ActiveSync

Bar Refael

March 3, 2024

Microsoft has resolved a problem that prevented some Microsoft 365 users’ Outlook desktop clients from connecting to email servers through Exchange ActiveSync (EAS). The issue, which only affected users who updated to Version 2401 Build 17231.20182 of Outlook for Microsoft 365, has been fixed in Version 2402 Build 17328.20068 and higher.

Key Points:

  • Exchange ActiveSync (EAS): EAS is a synchronization protocol used by Microsoft Exchange to allow users to access their email, calendar, contacts, and tasks.
  • Impact: The sync issue impacted Outlook for Microsoft 365 users, preventing their desktop clients from connecting to email servers via EAS.
  • Resolution: Microsoft has resolved the issue in Version 2402 Build 17328.20068 and higher. Users are advised to update their Outlook clients to this version.
  • Temporary Fix: Before the resolution, Microsoft provided a temporary fix that involved reverting Office M365 Click-to-Run installations to an unaffected build or switching to an Office Channel without the sync issue.


  • Operational Disruption: The sync issue likely caused disruptions for affected users, impacting their ability to access email and other data on their Outlook desktop clients.
  • Importance of Updates: The resolution highlights the importance of keeping software updated to address known issues and vulnerabilities.


  • Update Outlook Clients: Users should update their Outlook for Microsoft 365 clients to Version 2402 Build 17328.20068 or higher to resolve the sync issue.
  • Monitor for Updates: Regularly check for and apply updates to software to ensure security and functionality.
  • Backup Data: Regularly backup important data to prevent loss in case of synchronization issues or other problems.


Microsoft’s quick resolution of the Outlook sync issue over Exchange ActiveSync demonstrates the company’s commitment to addressing problems that affect its users. Organizations and individuals using Outlook for Microsoft 365 should ensure their clients are updated to the latest version to avoid similar issues and maintain secure and efficient communication.

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OP Innovate Research Team.

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