Full error message: GetQBCompanyName: exception: system.NullReferenceException: Object reference not set to an instance of an object. at BdSyncCore.Business.Sync.SyncManager.GetQBCompanyName(String qbFilePath)
The reason you are getting this error is that the company name is not populated in QuickBooks. This error occurs most often when there has been a recent conversion from QuickBooks Online to QuickBooks for Windows.
To resolve this sync error:
In QuickBooks click Menu > Company Information and check for the company name.
If the company name does not appear enter the name and then save.
If the company name does appear delete the name that appears, re-type it and save.