I'm trying to create an invoice and have been getting error messages saying "cannot connect to service try again later". This has been happening for a week.

Welcome to the Community space, @markhurleyaei. I understand that encountering runtime issues while creating an invoice in QuickBooks Online (QBO) can be time-consuming I'm here to help resolve this matter as soon as possible.

The error message "Cannot connect to service try again later" in QBO is a possible problem between your computer or device and the QBO servers. However, QuickBooks may sometimes exhibit strange behavior or experience performance issues caused by browser problems. 

Let's perform some basic troubleshooting steps to verify. We can first log in to your QBO account using private browser.

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

If there's no issue on using private browser, go back to your regular browser and clear its cache.  

You might also want to check out the article on system requirements for QuickBooks Online to ensure the best experience when using the platform.

Moving forward, we recommend reading these helpful articles on managing invoice-related tasks:

• Create invoices in QuickBooks Online
• Customize invoices, estimates, and sales receipts in QuickBooks Online

Come back to this post if you need additional help creating invoices in QuickBooks Online. I'll be around to provide further assistance. Keep safe.