I have a VB6 .exe program that opens Excel files and converts them to Access database files, among other things. Everything has been working well since the late 90s, and I have been able to keep everything working through all the versions of Windows through Windows 10 and Office up through 32-bit Office 2016. The program uses ADODB and works well.

Then, corporate IT decides to upgrade all employees to 64-bit Office 365. When the customer runs the program, "3706 - Provider cannot be found. It may not be properly installed" error pops up. I don't believe that I can debug the old VB6 app with VS 2017. I simply don't know exactly what VB6 code is causing the problem, but I think it is trying to open an Excel file because that is the first thing it does and it doesn't get past that point.

I have read many threads in the VB6 and earlier forum that say to avoid 64-bit Office but some say that it can work. If it were a serious Provider issue, why does it work with 32-bit Office 2016 and not with 64-bit Office 2019? Customer cannot go back as they are rolling out 64-bit Office to all employees and are committed. Any suggestions on 1) How to debug this issue, or 2) Can VB6 programs that use ADODB work with 64-bit Office 365?