Creating new invoice: I get error message: Select a product or service. I have selected product/service. 4 lines completed.

Let's ensure you can create the invoice without getting the error, 

johan-benade.

Too much cache in your browser can result in strange responses from the software, including errors and missing options. Let's perform a few troubleshooting steps to fix this. 

Log in to your account using an incognito/private browser to see if you can successfully create an invoice without the error. Please use these keyboard shortcuts:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox: press Ctrl + Shift + P
• Microsoft Edge: press Ctrl + Shift + P
• Safari: press Command + Shift +N

If everything works, let's clear the cache in your browser to start fresh and ensure optimal performance. If private browsing isn't successful, I suggest switching to a different supported web server as an alternative.

 I'm also adding this article for personalising your sales forms: Customise invoices, quotes, and sales receipts in QuickBooks Online.

If you need more assistance with managing invoices, come back here. I'm always around to help.