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You can download the QuickBooks Desktop (QBDT) 2020 trial version, to move your file to QuickBooks Online. Also, the error usually comes up when you're using an unsupported QuickBooks Desktop version (2013 or older).
Before doing so, you'll want to create a backup copy of your 2013 files and download a trial of QuickBooks Desktop. Then, use the license and product number found in this article: Download a trial of QuickBooks Desktop.
After downloading and installing the trial version, upgrade your company file so you can open it from QuickBooks Desktop 2020.
Once done, convert your QBDT file to QBO. Here's how:
You can refer to this article for details about moving your QuickBooks Desktop file to QuickBooks Online.
Also, note that some data might not convert to QuickBooks Online. Here's a complete list of what to expect after the conversion process: What to expect when you switch from QuickBooks Desktop to QuickBooks Online.
I've added our QuickBooks Support page. It contains articles, video tutorials, and more that'll guide you with QBO.
Should you have any other concerns or follow-up questions, you can always find me here. Have a pleasant day ahead.
Open your company file on the the trial license of QBD 2020 as mentioned by Joesem M. Make sure you have open a QBO account prior to proceed.
You may also look at speaking to a 3rd party provider who will do the conversion for you.