Thank you for your help.

I have some question on this

I am sending the POST request after creating the invoice as below

Endpoint=callout:QuickBook_Online3/v3/company/913034[removed]/invoice/41539?minorversion=65&include=invoiceLink, Method=POST

I am getting Response as 200 but within this response its showing error as

{"Fault":{"Error":[{"Message":"An application error has occurred while processing your request","Detail":"System Failure Error: java.lang.NullPointerException","code":"10000","element":"SystemFailureError"}],"type":"SystemFault"},"time":"2024-02-21T03:09:47.148-08:00"}

But what Request Body do we need to send in the POST Request, could you please help me with this, that would be great help.

Thanks again

Awaiting your reply.