I'm stepping in to offer further details regarding the issue you're encountering with the 'Payment can't be scheduled' message that appears when attempting to pay a bill, gilles.
Unexpected messages can happen sometimes when there's a browser-related issue. Thus, I recommend accessing your QBO account in a private browser, as suggested by 4Gal. It determines if the problem you're experiencing in QuickBooks is due to your browser settings or extensions.
- Google Chrome: Ctrl + Shift + N
- Mozilla Firefox and Microsoft Edge: Ctrl + Shift + P
- Safari: Command + Option + P
Then, clear the browser cache. Over time, the browser's cache gathers temporary files and data from the websites you browse. Clearing it can boost your browser's speed and overall performance. Lastly, you can use another browser because sometimes the issue may be browser specific.
Also, you may want to check out one of our Help pages as your reference in case you need a guide in entering expenses, paying bills, writing checks, and managing vendors in QBO: Expenses and Vendors help for QuickBooks Online.
If you have additional concerns managing bills and business expenses in QBO, please comment below. I'll be around to respond and assist you.