This error is being caused by QuickBooks and not Kennel Connection.  If you are running QBDL with the auto sync and get this message, if you disable the auto sync, you won't see this error any more.  

Please note:  The remedies below were recommended by Intuit as attempts to repair this error.  As this is not a Kennel Connection error, these will need to be completed by you, your technician or Intuit Support.

STOP:  Before proceeding with any of the steps below, make a backup of both your KC database and QB Company File to another location.

Remedy 1:  Update QuickBooks to the latest revision and try again.

Remedy 2:  

• Close Kennel Connection on all computers.
• Close QuickBooks.
• Backup your Kennel Connection database on the server/main computer using our Backup/Restore Utility.
• Go into the Windows Task Manager (ctrl, alt, del), go into processes and stop the QB program files.
• Open Kennel Connection and QuickBooks and try to sync.  Click on Utilities, QuickBooks DirectSync.

A note here:  The reason we go into the Task Manager to close QuickBooks is that QB has been known to not close fully.  You can go into the Task Manager, Processes and locate the QB32.exe files and manually end the process for each one.  Some clients are able to resolve this error by shutting down the QB process completely in Task Manager.  

Remedy 3:  Uninstall and reinstall QuickBooks.  

If this is not successful or you don't feel comfortable doing the steps above, you will need to contact Intuit for assistance.