I'm sending the COGS to QB from A2X, but it says error occured in sending the COGS to QB, could you explain this to me why it happens, what can I do to worked with it?

Hi there, amazon-bludotpro.

Thank you for posting here in QuickBooks Community. Let me route you to the right support to resolve the error that occurred when sending COGS to QuickBooks from A2X.

I recommend signing up and posting your question to our separate online forum called Intuit Developer Community. This site contains resources for software development, as well as the ability to ask fellow developers questions.

Here's how: 

1. Visit: https://help.developer.intuit.com/s/.
2. On the Intuit Developer page, go to the right-hand side.
3. Under Platform Status, look for QuickBooks Online Sandbox.
4. Choose between View Sandboxes, or Create New Sandbox.  
5. Login using your QuickBooks Online credentials.

Please check this article to see information on how QuickBooks handles inventory assets, average cost, and Cost of Goods Sold (COGS): Understand inventory assets and cost of goods sold tracking. This also provides details on how to compute for the average cost and know which report will help with inventory management.

Please don't hesitate to post again if you have other questions related to QuickBooks. I'm always here to help.