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Avalara Help Center

Why am I getting the error "CB-201: Object reference not set to an instance of an object"?


When opening QuickBooks, AvaTax will try to start up and/or when attempting to test connection error "CB-201: Object reference not set to an instance of an object" will populate preventing AvaTax from running.


QuickBooks Desktop


  • This issue is caused by multiple versions of AvaTax trying to run.
  • Make sure there is only one version of AvaTax installed.
    • You can check this by looking at your installed programs list.
  • If you have multiple computers that use AvaTax and Quickbooks together, make sure they are all on the same AvaTax for QuickBooks version.
  • End all QuickBooks and Avalara processes in the TaskManager
    • Go to C:\Program Files (x86) > Avalara > AvaTaxAdapter  > Bin folder
    • Right click on the file names below and Run as Administrator (Must follow order sequence).

      • Unsubscribe.exe
      • Subscribe.exe
      • unregister_for_Adapter
      • unregister_for_callback
      • register_for_Adapter
      • register_for_callback
    • Open QuickBooks (right click on icon and run as Administrator)
    • Log into QuickBooks as an Admin.