Why the sync error occurs

This error can occur for several reasons:

• The user syncing needs to be logged in as an Administrator in the QuickBooks file
• The user syncing needs to be logged in Single-User Mode
• Bill.com needs to be an Integrated Application in QuickBooks

How to fix the sync error

• Make sure the user syncing needs is logged in as an Administrator in the QuickBooks file
• Make sure the user syncing is logged in Single-User Mode
• Make sure Bill.com is an Integrated Application in QuickBooks:
  1. In QuickBooks on the top tool bar, select Edit>Preferences
  2. Select Integrated Applications
  3. Select the Company Preferences tab
  4. Highlight Bill.com and select the check box to allow access
  5. Go to the Sync Dashboard and select Sync. When the application certificate pops up, select the checkbox for Yes, always allow access even if QuickBooks is not running