When connecting a bank account, what specific error message did you encounter? And which bank are you trying to connect to QuickBooks Online (QBO)? Please provide any additional details or screenshots to help us provide a tailored answer.
To resolve this issue, start by signing out of your QBO account and signing back in. Then, reconnect your bank account.
Make sure you’re using the correct username and password for your bank account. You can check this by logging into your bank’s website directly. If you can access your account there successfully, use the same login details when connecting your account in QuickBooks Online.