"If you are looking forward to the ways to convert your QuickBooks Desktop to Online, you need to begin with keeping your QuickBooks Desktop updated to its latest version that is available, as the old and outdated version will lead to many issues in importing your data to QuickBooks Online.
First, log in as the admin and type in your administrator details. Then, from here, if you see the error message of “Your File Size Is Too Big,"" you are required to fix it. Now, fix every data error present. You are good to go!"