If your stock/inventory on SelluSeller does not match with that of the marketplace, you can perform a Stock Sync from SelluSeller.
- Login to SelluSeller and go to the Inventory Tab. Click on Stock Sync button ( at extreme upper right corner) and select the marketplace with which you wish to sync stock.
Hope this answers your question.
You can resolve this error in SelluSeller, by clicking here.