I applied Service Pack 4 on secondary node of an Availability Group. It failed so I restored the whole VM for the secondary node to an earlier version, and now the data is not synchronizing.

I have active and passive two nodes. I tried to resume the data movement manually. But it failed. Can you suggest anything here?

  • What error you get ? Restoring whole VM in an AOAG topology is not a good idea !
    – Kin Shah
    Jun 7, 2018 at 14:37
  • 2
    Back up from primary, restore on secondary, set up always on. The LSN's have to be in sync. When you restored a VM that broke the log chain.
    – Alen
    Jun 7, 2018 at 16:00

1 Answer 1


When you restored the VM, its LSN was no longer in sync with the primary and thus it can't be resumed. The primary is too far ahead to resume.

You'll need to drop the secondary and add it to the Availability Group again in order to resume synchronizing. You can do this with an existing FULL backup plus the LOG chain.

  • Yes the LSN chain is broken and i had to manually add the databases back to the availability group using Full backups.
    – Pol
    Jun 11, 2018 at 15:14
  • @PolDBQ, be sure to mark my answer as the answer then. ;-)
    – Tara Kizer
    Jun 12, 2018 at 16:09

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