Hi there, BoatdockOCPP.
Thank you for reaching out the QuickBooks Community. Allow me to help you get past the error message so you can attach a document to a bill or an invoice.
Unrecoverable error in QuickBooks Desktop could be caused by data damage in the company file for specific users, an application issue, and system or computer issues.
Here's an article that will guide you on how to fix unrecoverable error in QuickBooks Desktop: https://community.intuit.com/articles/1532123.
Since this only happens when you upgraded from Office 2010 to Office 2016, there is a possibility that the error is due to the operating system not meeting the requirement for your version of QuickBooks Desktop.
Check out this article to know more about the system requirements for QuickBooks Desktop 2015: System requirements for QuickBooks 2015 and Enterprise Solutions 15.0.
I hope this helps. Feel free to reach out to us if you have any other questions. Wishing you continued success!
