Who is this for? All individuals who are encountering error 99003.
This error occurs when you are setting up a parentage, but a required value is missing for the specified variation theme. The screenshot below is an example of a processing report error message showcasing the 99003 error.

The example below shows a parentage setup with a SizeName variation theme. However, the Size column of child listings is not filled out.

To fix this, rework your flat file by providing the Size value for each child listing in the Size column. Save and resubmit your feed.

You can check out the SOP: Parentage Creation.