Welcome to the Community forum, @lissa-hbsx-com.
I'm happy to provide you information about moving your file from QuickBooks Desktop (QBDT) to QuickBooks Online (QBO).
To ensure we're on the same page, can you please verify the error message encountered when converting? This is for me to provide the best resolution for you.
For the detailed steps when importing your company file, as well as what to expect and do next after the conversion, please refer to the additional references:
If you get the same error, I recommend the following article about how to fix the error during or after conversion: Resolve Common Errors When Converting Data.
Please let me know how things go on your end. I'll be happy to help you in any way I can. Take care.