Merchant Center item_group_id errors explained

Use item_group_id when products differ by supported variant attributes such as color, size, pattern, material, age group, or gender where applicable. The shared value tells Google that those separate offers belong to one variant family.

The value is an internal grouping key, not necessarily a customer-facing identifier. Keep it stable while the product family remains the same.

The id field identifies one exact submitted offer and must be unique in its account context. item_group_id identifies the relationship among several offer IDs. A red shoe in size 40 and the same shoe in size 41 should not overwrite each other, even though they may share one group.

Grouping failures can distort product selection and create downstream mismatch diagnostics.

• Using one product ID for every variant
• Assigning a different group ID to each child
• Grouping unrelated styles or bundles
• Reusing a group value across different parent products
• Omitting the attribute that actually distinguishes variants
• Submitting parent price, availability, image, or GTIN for every child

List every purchasable variant and verify unique IDs, one appropriate group ID, differentiating attributes, variant-specific identifiers, price, availability, images, and URLs. Then inspect Merchant Center's processed products rather than only the source export.

CommerceVigil preserves Merchant product identity and avoids fuzzy performance matching. It can report affected variants and direct issue evidence, but it does not regroup products or decide which catalog items belong together.