Hello there, Jadehc.

Let's make sure that the previous submission did not go through to avoid duplication.

1. Click Taxes.
2. Choose Payroll Tax.
3. Click Annual Taxes
4. Select W-2 form, and check if the submission is successful.

If not, let's submit the W-2 form. Before that, let's try these browser steps first.
 

First, use the Incognito window. If it works well, you can go back to the main browser and clear cache. If you're still getting the same error, you can use different browsers such as Mozilla Firefox, Internet Explorer or Google Chrome. 

Let me know if you need more help.