How can I fix inventory file upload error of ASIN already exist in amazon?

Amazon will email you the errors that you have got in your inventory file. You can check them and change those attributes on which you have got errors and again try to upload the inventory file. Otherwise, on the right side of your inventory file upload, you have the option to complete your draft. Here Amazon will redirect you to the errors. You can manually change them through the complete draft option.

Check out you listing backend it will show you the missing attributions or may you have not completed your listing’s draft then Amazon will direct you to the errors. You can change them manually by using the complete draught option.