Unable to add bank account. Getting errors while adding.

Welcome to the Community, @nidhi-sharma-abb. I'm here to help you fix your banking concerns. 

May I know the error code you received while adding it? This will help me in providing you with the correct steps. 

On the other hand, when you're unable to add, find, or connect, you may experience either of the following scenarios with your bank:

• Your bank has multiple names on our list. Make sure you have selected the correct listing or have tried all possible links.
• Your bank doesn't connect to all types of accounts.
• Your bank isn't a participating financial institution.

You can visit this link to learn more about adding your bank account to QuickBooks Online.

For future reference read through this article to get more ideas on categorising online bank transactions in QuickBooks Online.

Feel easy to visit us again should you have more concerns. I'll be around to guide you again.