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Entra ID

How to Fix Entra Connect: Stopped-extension-dll-exception

Last reviewed

Error message

Synchronization Service Manager reports stopped-extension-dll-exception on a connector run.

Extension DLL exceptions are rare but disruptive — they stop sync entirely for that connector until cleared.

What this error means

An Entra Connect rule extension threw an unhandled exception during a sync run, halting that connector's run profile.

Why this happens

Custom synchronization rules with bad logic, schema mismatch (a referenced attribute doesn't exist on a partition), or an Entra Connect agent that needs an update.

Quick fix (for end users)

  • Open Synchronization Service Manager → Operations → find the failing run.

Admin / engineer fix

  • Capture the exception details from the failing run.

    command
    miisclient.exe

  • Review your custom synchronization rules for any that reference attributes which don't exist on all partitions.

  • Update Entra Connect to the latest version. Microsoft regularly fixes sync engine bugs.

Step-by-step fix

  1. Identify the failing run via Synchronization Service Manager.

  2. Read the exception details to find the bad rule.

  3. Fix the rule and re-run sync.

Affected products

Microsoft Entra Connect

Common variations of this error

People also see these phrasings of the same problem:

  • Stopped-extension-dll-exception

Still broken? Try these

  • Disable the suspect rule temporarily to confirm it's the source.
  • Open a Microsoft case — sync extension exceptions sometimes require Microsoft engineering to diagnose.

Related errors

Related searches

  • entra connect rule extension error
  • synchronization service manager errors

Frequently asked questions

What does "Entra Connect: Stopped-extension-dll-exception" mean?

An Entra Connect rule extension threw an unhandled exception during a sync run, halting that connector's run profile.

What causes "Entra Connect: Stopped-extension-dll-exception"?

Custom synchronization rules with bad logic, schema mismatch (a referenced attribute doesn't exist on a partition), or an Entra Connect agent that needs an update.

How do I fix "Entra Connect: Stopped-extension-dll-exception"?

1. Identify the failing run via Synchronization Service Manager. 2. Read the exception details to find the bad rule. 3. Fix the rule and re-run sync. Always test changes in a non-production environment first.

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