Your QuickBooks Online account can be disconnected for a variety of reasons. It might be that your subscription has expired, you’ve changed the login credentials, or the period that you’ve authorized API Nation connection is over. Whichever case it may be, you can reconnect your Quickbooks Online account in three simple steps.
Go to Accounts. You should see an exclamation mark by the account name that is disconnected.
Click the exclamation mark and log into QuickBooks Online to reconnect your sync.