How to fix QuickBooks error 9999 (banking code)
                     How to resolve Quickbooks 9999 error code
There are multiple symptoms associated with Quickbooks error 9999
● Users of QuickBooks Online cannot sync their banking information.
● You will lose access to the web browser and the process will slow down.
● You'll see a dialog box saying "Sorry, we're unable to update your account.". You 
can try again if it doesn't work. 
How to solve this 9999 error
Reconnect with your bank
● The left side panel has two categories: Banking and Banking.
● Select the Edit icon for the account you wish to disconnect.
● You must check the Disconnect this account on the Save screen of 
Account.
● Click on the Save/Close button.