Possible reasons behind the QuickBooks desktop error 40003

1. Check if the firewall settings on your device are set up correctly because they could be the root of the error on your desktop.
2. An unstable internet connection could cause the QuickBooks desktop error 40003.
3. Another potential cause of this error could be a damaged file or QB component.

Solutions to fix the QuickBooks payroll update error 40003

Solution 1: Attempt to update your QuickBooks manually

1. In QB, go to the help menu and choose Update QB Desktop.
2. Choose the "reset the update" option after clicking on Update now.
3. Then select "Get Updates."
4. Let the Update download.
5. When QuickBooks is finished, reopen it.
6. From the help menu, pick Update QB.
7. Make sure to select Update Now after choosing Overview.
8. Let the process finish.
   
   Implement the second solution if the first solution did not help you fix this error in QuickBooks.

Solution 2: Utilize the verify and rebuild data tool

1. To locate the QB desktop, use the Windows search bar.
2. Right-click, then select "run as administrator."
3. In QB, pick the file tab to access the file menu.
4. After selecting Utility, click Verify Data.
5. A pop-up will prompt you to fix any bugs it finds.
6. If there is no such error, a pop-up stating "QuickBooks found no problem with your data" will appear.
7. To fix the error, you can select the Utility option and click the File tab again.
8. To determine whether the payroll error has been fixed, use the verify tool to check the data.
9. Try downloading the payroll updates after restarting your computer.

Summing it up!