Hello Lilies2735-goog, thanks for posting on the Community page, in order for us to help resolve your issue, please could you provide us with more information thanks. What bank is it? Is it a new connection or a reconnection? Are you getting any error messages or codes showing up? Are you doing this on the app version or the web browser version of Quickbooks?
This error means that the connection between your bank account and QuickBooks Online has expired and needs to be re-established for a further 90-day period.
Remember to review the bank transactions QuickBooks downloaded before reauthorising the connection. This will prevent duplicate transactions from being downloaded when you reconnect.