Reason: Seller is blocked by their MerchantConfig. 

This error means that there is some issue with Seller Profile in Seller Central. It could be an account verification issue, or infringement or other kind of violation on the seller account.  If you see this error, please check your account For Performance notifications in Seller Central to see if there is any message from Amazon which resulted in this error.

You may also contact Amazon and resolve this issue.