Can I disable the Magento Inventory modules?

Question

I have my stock synchronized and managed by SAP, because of it I'm having issues with the inventory quantity vs salable quantity, I won't use multi-source inventory in this project,

can I disable all the Magento_Inventory modules and not have issues?

    'Magento_Inventory' => 1,
    'Magento_InventoryAdminUi' => 1,
    'Magento_InventoryAdvancedCheckout' => 1,
    'Magento_InventoryApi' => 1,
    'Magento_InventoryBundleProduct' => 1,
    'Magento_InventoryBundleProductAdminUi' => 1,
    'Magento_InventoryCatalog' => 1,
    'Magento_InventorySales' => 1,
    'Magento_InventoryCatalogAdminUi' => 1,
    'Magento_InventoryCatalogApi' => 1,
    'Magento_InventoryCatalogSearch' => 1,
    'Magento_InventoryConfigurableProduct' => 1,
    'Magento_InventoryConfigurableProductAdminUi' => 1,
    'Magento_InventoryConfigurableProductIndexer' => 1,
    'Magento_InventoryConfiguration' => 1,
    'Magento_InventoryConfigurationApi' => 1,
    'Magento_InventoryDistanceBasedSourceSelection' => 1,
    'Magento_InventoryDistanceBasedSourceSelectionAdminUi' => 1,
    'Magento_InventoryDistanceBasedSourceSelectionApi' => 1,
    'Magento_InventoryElasticsearch' => 1,
    'Magento_InventoryExportStockApi' => 1,
    'Magento_InventoryIndexer' => 1,
    'Magento_InventorySalesApi' => 1,
    'Magento_InventoryGroupedProduct' => 1,
    'Magento_InventoryGroupedProductAdminUi' => 1,
    'Magento_InventoryGroupedProductIndexer' => 1,
    'Magento_InventoryImportExport' => 1,
    'Magento_InventoryCache' => 1,
    'Magento_InventoryLowQuantityNotification' => 1,
    'Magento_InventoryLowQuantityNotificationAdminUi' => 1,
    'Magento_InventoryLowQuantityNotificationApi' => 1,
    'Magento_InventoryMultiDimensionalIndexerApi' => 1,
    'Magento_InventoryProductAlert' => 1,
    'Magento_InventoryRequisitionList' => 1,
    'Magento_InventoryReservations' => 1,
    'Magento_InventoryReservationCli' => 1,
    'Magento_InventoryReservationsApi' => 1,
    'Magento_InventoryExportStock' => 1,
    'Magento_InventorySalesAdminUi' => 1,
    'Magento_InventoryGraphQl' => 1,
    'Magento_InventorySalesFrontendUi' => 1,
    'Magento_InventorySetupFixtureGenerator' => 1,
    'Magento_InventoryShipping' => 1,
    'Magento_InventorySourceDeductionApi' => 1,
    'Magento_InventorySourceSelection' => 1,
    'Magento_InventorySourceSelectionApi' => 1,
    'Magento_SalesInventory' => 1,
    'Magento_ScalableInventory' => 1,
    'Magento_InventoryShippingAdminUi' => 1,
    'Magento_CatalogInventoryStaging' => 1,

Answer 1

Depending on the modules that you have installed disabling all the Magento_Inventory modules might cause issues, so I recommend installing this module below to disable the stock reservation.

composer require ampersand/magento2-disable-stock-reservation
bin/magento setup:upgrade
bin/magento module:enable Ampersand_DisableStockReservation

Both the inventory and cataloginventory_stock should be in the same mode (Update on Save or Schedule) for this module to work as expected.

If you are running this on Schedule you should have CRONs activated.

This module will:

• Prevent all writes to the inventory_reservations table. It does so by using an around plugin on PlaceReservationsForSalesEventInterface
• Trigger stock deductions on order placement. See inventory_sales_source_deduction_processor observer on sales_order_save_after event.
• Prevent stock deductions on order shipment. See disabled inventory_sales_source_deduction_processor observer on sales_order_shipment_save_after event.
• Replenish stock for cancelled order items. See inventory observer on sales_order_item_cancel event.

Alternative

If you have just few third-party modules and you're sure that disabling is not causing issues you can just run this command below to disable all Magento_Inventory modules.

php bin/magento module:status | grep Magento_Inventory | grep -v List | grep -v None | grep -v -e '^$' | xargs php bin/magento module:disable

Answer 2

Magento Inventory (MSI) documentation

Source Management - https://docs.magento.com/m2/ce/user_guide/catalog/inventory-sources.html

Stock to Source assignment - https://docs.magento.com/m2/ce/user_guide/catalog/inventory-about-sources-stocks.html

Reservations - https://devdocs.magento.com/guides/v2.3/inventory/reservations.html

https://docs.magento.com/m2/ce/user_guide/catalog/inventory-about-order-status-reservation.html

Source Selection Algorithm - https://devdocs.magento.com/guides/v2.3/inventory/source-selection-algorithms.html

https://docs.magento.com/m2/ce/user_guide/catalog/inventory-about-ssa.html

Order workflow diagrams - https://github.com/magento/inventory/wiki/Salable-Quantity-Calculation-and-Mechanism-of-Reservations#description-of-order-processing

https://github.com/magento/inventory/wiki/Shipment-and-Order-Management

MSI + Backorder - https://docs.magento.com/m2/ce/user_guide/catalog/inventory-backorders.html

This will help you to better understanding.