Hi Pradeep,
Thank you for reaching out regarding your concerns. The 'NO_CUSTOMER_FOUND' error occurs when the customer/account specified in your request header is indeed not found or is not a valid account. Could you please verify if you are passing the correct client customer Id? If the error persists, could you please share the client customer id and the complete request and response logs without redacting any information for further investigation on our end?
P.S. Please use Reply privately to author option while sharing the details.
Regards,
Nikisha Patel, Google Ads API Team