In a SQL Server FCI configuration, what happens to transactions that are in flight when the failover event happens? 1. If the transaction is committed just before the server crashes 2. If the transaction is just about to be commited and the failover event occurs.

Does a message get sent to the application? If the user has not yet commited and the failover happens, does the user get a message that the transaction is rolled back or what exactly happens to help the user know what to do?

From what I have read, the failover is automatic and it is transparent to the user. Is this completely true?

Thank you.

  • Point of clarification. Failover can be automatic, or you can elect to control when it happens. You may wish to control it in order to prevent ping-pong failovers. Jun 3, 2021 at 16:43
  • @JonathanFite, thanks, helpful comment, appreciated.
    – PTL_SQL
    Jun 4, 2021 at 11:42

1 Answer 1


On failover the clients' network connections are broken, and in-flight transactions are rolled back as part of the recovery process on the other server. The client will get an error message, most often related to the broken connection, and will need to reconnect to the server.

Clients without an in-flight transaction may be transparently reconnected to the new server.

  • thank you so much for that helpful response, very much appreciated.
    – PTL_SQL
    Jun 4, 2021 at 11:41

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