I have been getting (An unexpected error occurred. Please try again later.) message when I try to access my invoices. This has been an ongoing problem for the past week+?

Hello there, @rsversteegh-gmai. I've got here some steps to ensure you'll be able to access your invoice without error in QuickBooks Self-Employed (QBSE). 

To begin, let's make sure that your computer meets the minimum system requirements to run the program. The following computer operating systems and internet speeds are recommended to experience optimal QBSE performance: 

• Windows PC: Windows 10, Intel Core i3, or a comparable processor (2013 or newer) with at least 2 GB of RAM.
• Mac: OS X El Capitan 10.11 or newer.
• Internet connection: 1.5 Mbps.

For more details, feel free to check this article: System requirements for QuickBooks Online, Accountant, Payroll, and QuickBooks Self-Employed.

If confirmed that this is not the case, you can perform some browser troubleshooting steps to resolve the issue. Encountering errors when doing QBSE tasks is sometimes caused by a piled-up cache in your browser. The initial step to fix this is using an incognito mode. This does not store cache and will provide a clean slate. Below are the shortcut keys you can use:

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

Once signed in, access the invoice again. If this works, go back to the regular browser and clear the cache to eliminate the stored junk files. If not, you can utilize other supported browsers or devices. Might be that the current one you're using has a temporary issue with the program.

The program will also allows you to print invoice, export them as PDFs, and email reminders for overdue ones. To do so, simply go to the Invoice page and select the drop down arrow of the transaction under the Action column. 

I'd love to know updates on how the recommendation goes. If you have additional questions about accessing invoices in QBSE, please leave a reply below. I'm always here ready to lend a hand. Have a great day ahead.