Why a blank CSV cell is not the same as no change

The rule that causes accidental erasure

Shopify’s product CSV documentation distinguishes between a column that is present with a blank cell and a column that is absent from the import. With overwrite enabled, a blank non-required value can replace the live value with blank. If a non-required column is omitted, the existing value generally remains.

See Shopify’s official sections on overwriting product details and column dependencies.

Why “delete every column I am not editing” is incomplete advice

Reducing an update file is useful, but variant fields have dependencies. Shopify warns that fields such as SKU or weight depend on the matching option columns. If you include variant data without the required option identity, Shopify can create a default variant and remove existing variants.

For an update, keep the required URL handle and Title headers. When changing variant-level data, also retain the option name and value columns needed to identify those variants.

A safer overwrite workflow

1. Export products immediately before editing and keep that original untouched.
2. Work on a copy. Decide exactly which field groups you intend to change.
3. Compare the edited file to the untouched export and inspect every change outside that intent.
4. Build a focused update file that omits unrelated columns instead of leaving them blank.
5. Import a small product subset first, then verify products, variants, images, price, and inventory in the admin and storefront.
6. Only then run the larger import. Keep the original export until verification is complete.