Banking error 103 means that your banking credentials in QuickBooks Online don’t match what your Financial Institution (FI) has on file.
If you have an existing connection and you recently changed your banking credentials (username or password) on your FI’s website, perform the following steps in your QuickBooks Online company.
When entering your credentials, be sure to enter your username and password directly instead of allowing the browser to auto-fill your login credentials.
From the left menu, select Banking, and choose Banking.
Select the pencil icon.
Select Edit sign-in info.
Enter your new credentials and select Update.
If you are connecting for the first time, be sure to select the right bank and enter your banking credentials (username and password) correctly by performing these steps in QuickBooks Online:
From the left menu, select Banking.
On the Banking page, select Add Account.