Let's get this sorted out so you can update your bank and credit card accounts in QuickBooks Online.
Could you tell me which bank are you getting the error with? We've recently received reports that some of our customers are unable to update their bank feeds.
The error 9999 is a script that interrupts the connection between your financial institution and QBO. You can report your online banking problem straight to our engineers. They'll investigate what's causing the error and fix it for you.
On the error message, select ReportIssue.
Enter your name and email address, then select Submit.
Once the issue is resolved, you'll receive an email directly from the team that resolves banking errors.
In the meantime, let's perform some basic troubleshooting steps by opening QBO in a private window. This mode disables the cache from saving your data, and it's a good way to check issues caused by a full cache. As an alternative, you can use other supported browsers.
Keep me posted on how this goes and I'll get back to you.