I'm trying to validate a merchant for web from my server but I keep being met with a 400 response with the following error message: Payment Services Exception Invalid session request -- missing domainName The body I am sending is as follows (using dummy values): { "merchantIdentifier":"merchant.com.company.TestMerchant", "domainName":"frontend.example.com", "displayName":"My Store", "initiative": "web", "initiative_context": "frontend.example.com" } frontend.example.com is a verified domain so it looks right to me. Am I possibly missing something? or misunderstanding something? I haven't found any other queries about this specific error so I am creating one here. Any help would be greatly appreciated. Thanks :)