Fix it now · Microsoft Deadline Calendar
Entra Connect Sync must be on 2.6.84.0 by April 7, 2027
Microsoft moved the Entra Connect Sync deadline from September 30, 2026 to April 7, 2027, and raised the minimum version from 2.5.79.0 to 2.6.84.0. By April 7, 2027, every Connect Sync server must run 2.6.84.0 or later and use application-based authentication, or all synchronization fails until you upgrade. Upgrading alone doesn't switch an existing server over; run the wizard.
Fix it now
- On the Entra Connect server, check the installed version (Programs and Features, or the Entra Connect wizard).
- If it's below 2.6.84.0, plan the upgrade now. Download the latest Entra Connect Sync release from the Microsoft Entra admin center (it's only distributed there). Upgrading with an existing ADSync database? Use 2.6.91.0 or later: Microsoft lists an install failure for 2.6.84.0 in that case.
- Upgrading doesn't switch an existing server to application-based authentication. Run the Entra Connect wizard and configure it.
- Confirm a successful sync cycle in Synchronization Service Manager.
- Check your Entra Connect Health agents are 4.5.2466.0 or later.
- Note the version you're on and its retirement date. Put it on a calendar with an owner.
Why this keeps happening
Microsoft retires each Entra Connect version on a published schedule, and it changed this deadline and the minimum version on two consecutive days. The notice went to whoever owned that server when it was set up. See the full Microsoft Deadline Calendar.
What breaks next
- ChangedSept 30, 2026Microsoft moved the Entra Connect Sync deadline from Sept 30, 2026 to April 7, 2027, and raised the minimum from 2.5.79.0 to 2.6.84.0 (Sept 29 on its security hardening page, Oct 1 on the hardening page). Sync did not stop on Sept 30.Who it hits: Every campus syncing on-prem AD to Entra with Connect Sync below 2.6.84.0Source: Microsoft Learn: Hardening updates for Microsoft Entra Connect Sync (changed Sept 30 and Oct 1, 2026)
- NextOct 23, 2026Entra Connect 2.5.79.0 retires (it met the old deadline, but it is below Microsoft's new 2.6.84.0 minimum)Who it hits: Campuses that upgraded to 2.5.79.0 for the old Sept 30 deadlineSource: Microsoft Learn: Entra Connect version release history
You'll fix this one. There are more coming.
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Run the 5-minute Microsoft Deadline Check →Questions
Did sync stop on September 30, 2026?
No. On September 30 Microsoft moved the deadline to April 7, 2027. If your sync has stopped, the cause is something else: check the server's event log and your Entra Connect Health alerts.
Is 2.5.79.0 enough?
Not anymore. On October 1, 2026 Microsoft raised the minimum to 2.6.84.0, and 2.5.79.0 itself retires October 23, 2026.
Should we move to Entra Cloud Sync instead?
Possibly. Microsoft is encouraging it, but Cloud Sync doesn't support every Connect feature, such as advanced custom sync rules. Inventory your sync rules first.
Why does this matter for security?
If sync stops, accounts you disable on-premises stay active in the cloud.