Error 90001 — Variation theme missing or invalid

You submitted a parent-child variation listing but didn't specify a variation_theme, or you used a theme that doesn't exist for your product type (e.g., 'SizeColor' isn't valid for some categories).

Amazon requires every variation parent to declare HOW its children differ — e.g., by Size, Color, Size+Color, Style, etc. Each product type has a fixed set of allowed variation themes.

1. Look up valid variation themes for your product type in the Seller Central → Inventory Template for that category.
2. On the parent product, set variation_theme to one of the allowed values exactly (case-sensitive).
3. Make sure each child has the corresponding variation attributes filled in (e.g., for SizeColor theme, every child must have both size and color).
4. Resubmit the parent first, then the children.

• Using 'SizeColor' for apparel when only 'Size-Color' (with hyphen) is valid for some categories
• Mixing themes — half the children variant by Size only, half by SizeColor