[Bug]: Enabling manage_inventory on an existing variant does not create an inventory item

[nimbusparis]

Package.json file

{
  "name": "@dtc/backend",
  "version": "0.0.1",
  "dependencies": {
    "@medusajs/admin-sdk": "2.14.2",
    "@medusajs/admin-shared": "2.14.2",
    "@medusajs/caching": "2.14.2",
    "@medusajs/cli": "2.14.2",
    "@medusajs/dashboard": "2.14.2",
    "@medusajs/draft-order": "2.14.2",
    "@medusajs/file-s3": "2.14.2",
    "@medusajs/framework": "2.14.2",
    "@medusajs/medusa": "2.14.2",
    "@medusajs/notification-local": "2.14.2",
    "@medusajs/ui": "4.1.9",
    "@tanstack/react-query": "5.64.2",
    "zod": "4.2.0"
  },
  "devDependencies": {
    "@medusajs/test-utils": "2.14.2",
    "typescript": "^5.6.2"
  },
  "engines": { "node": ">=20" }
}

Node.js version

v22.23.1

Database and its version

PostgreSQL 16.14

Operating system name and version

Alpine Linux v3.24 (conteneur Docker, node:22)

Browser name

Chrome (Admin dashboard)

What happended?

The Product Variant Inventory docs state that an inventory item is created automatically when a variant is created with manage_inventory: true or updated to enable manage_inventory.

Only the create path actually works. Toggling manage_inventory from false → true on an existing variant — via the Admin dashboard, or POST /admin/products/:id/variants/:variant_id with { "manage_inventory": true } — flips the boolean but does not:

• create an inventory_item,
• create the product_variant_inventory_item link.

The variant ends up with manage_inventory = true but no linked inventory item, so it never shows up under Inventory, and there is no way in the Admin UI to associate an existing inventory item with the variant. The merchant is stuck.

This is a very common scenario: converting a made-to-order product (inventory not managed) into a stocked one after it was created.

Expected behavior

Enabling manage_inventory on an existing variant creates the inventory item and the variant↔item link, exactly as it does on variant creation (per the docs). Alternatively, the Admin dashboard exposes a way to create/associate an inventory item for an existing variant.

Actual behavior

Only product_variant.manage_inventory is updated to true. No inventory_item row is created, no product_variant_inventory_item link is created, and the Admin offers no UI to fix it. Verified in the DB:

• product_variant.manage_inventory = true
• SELECT * FROM product_variant_inventory_item WHERE variant_id = '' → 0 rows
• no matching inventory_item

Link to reproduction repo

Reproducible on a vanilla install — no custom code needed: 1. npx create-medusa-app@2.14.2 repro && cd repro 2. Admin → create a product with one variant, Manage inventory OFF. 3. Edit the variant → Manage inventory ON → Save. 4. Go to Inventory: no inventory item exists for that variant. DB confirms manage_inventory = true with no inventory_item / no product_variant_inventory_item link. Happy to push a minimal repro repo if required.

[medusa-os-bot]

Thanks for reporting this! We've labeled it as a bug and will investigate.

When a product variant is updated with manage_inventory toggled from false to true, the update workflows (updateProductVariantsWorkflow, updateProductsWorkflow) do not create an inventory item or the product_variant_inventory_item link — only the boolean flag is updated. The create path correctly creates both the item and the link, but the update path only handles the reverse direction (true → false, dismissing existing links). There is no inventory creation logic for the false → true transition in any update workflow. Confirmed on Medusa v2.14.2. The Admin UI also offers no way to manually associate an inventory item with an existing variant, leaving merchants unable to recover without direct API calls. Relevant files: packages/core/core-flows/src/product/workflows/update-product-variants.ts and update-products.ts.