To sync inventory with Shopify in OneCart, you need to ensure that your skus in OneCart is mapped to a Shopify location. 

First, make sure you have at least one location set up in your Shopify store.
Go to Shopify > Settings > Locations, and click 'Add location' to create a new one.

Add a location (In Shopify)

You can add a location. After you create a location, it’s added to the bottom of your fulfillment priority list.

Steps:

Desktop

  1. From your Shopify admin, go to Settings > Locations.

  2. In the All locations section, click Add location.

  3. In the Location details section, add your location name:

    • In the Name section, click Add.
    • Enter a location name, and then click Done.

  4. In the Location details section, add your location address:

    • In the Address section, click Add.
    • Enter a location address, and then click Save.

  5. Optional: To make your inventory available for online purchases at this location, in the Fulfillment details section, select Fulfill online orders from this location.

  6. Click Save.


Map your OneCart skus to Shopify Location

During the import listings and matching under the column "Shopify Location" select the desired shopify location you would like to map to.



You can learn more here - https://help.getonecart.com/help/matching-your-platform-listings-in-onecart