Thank you for the quick reply, @781.

To isolate the problem you're having, you can try using other supported browsers when trying to print deposit slips in QuickBooks Online. Or, use other printers when printing.

If you're getting the same error, I encourage contacting our Support Team as suggested above to check and review this further securely. To contact, tap on Contact us from the Help menu.

Also, read this article to learn more about setting up and printing deposit slips in QuickBooks Online.

Get back to me if you have any other questions. I'm always here to help. Wishing you a good one!