You see this message:
Error Code: 6_1015: Unable to upload your data possibly because of a problem with your company file. Please use the QuickBooks File Doctor Tool to solve this problem.
This error is caused by a problem in your company file.
Solution 1: Make sure Intuit Sync Manager is on the latest release.
Solution 2: Download, install and run the QuickBooks File Doctor Tool with Force DataSync fix enabled
Important: You must install the tool on the same computer with the company file that had the sync error and the QuickBooks application used to open that file.
Note: You do not need to clear sync settings before running this tool.
Note: Depending on the size of your company file, it may take 10 minutes or longer to complete the diagnosis and repair. Be sure to let the tool complete the process.