Is there a way to resolve error 4000 when connecting to bank? I am having trouble connecting my bank which was connected and working great.

Hello, jamiejohn.

You'll see this error if your QuickBooks account has more than 4,000 categories. You can use the standard method in connecting your bank account to QuickBooks Online (QBO). Let walk you through with the steps.

1. On the left pane, select Banking. 
2. Go to the Banking tab.
3. Click on Add Account.
4. Locate your financial institution and select it from the list.
5. Enter your updated Login ID and password and click on Continue.
6. Complete the security verification steps and select Securely connect.
7. Choose the bank emblem of the account you want to connect in QuickBooks.
8. In the Account type drop-down menu, choose either the Bank or Credit Card account.
9. Click Connect.

For future reference, I have included these banking help articles in case you have other questions.

Please touch base with us if there's anything else you'd like to help you with. We're always right here to assist.