Suddenly the bank connection does not work and it shows error 590. How to fix it? Thanks

In QuickBooks Online, bank error 590 means an issue on your bank's end is blocking transaction syncing with QBO, Dixon FDS.

To resolve this issue, try reconnecting your bank account to QuickBooks, and if the problem continues, I recommend contacting your bank, as they can determine if any system updates or disruptions are affecting the integration.

For additional details, you can consult this article to learn how to resolve bank errors in QBO: Troubleshoot bank connection issues in QuickBooks Online. 

Feel free to reach out if you need further details about bank errors in QBO. We're here to assist you anytime.