Hi @Tim ter Laare,
App Service Domain resources are not like other Azure resources. They are internally tied to a "shopper ID" in Azure’s domain reseller system (GoDaddy/Domain Registration System), and this linkage is subscription-specific and non-transferable in many cases. When you try to migrate the domain resource between subscriptions even in the same tenant, it fails because the backend system still associates the domain with the original subscription's billing identity (shopper). This is also why Advanced Management cannot retrieve contact info; the management system no longer recognizes it under your new context.
Unfortunately, Azure App Service Domains cannot be moved across subscriptions using normal Resource Group migration, even within the same tenant. This is a known limitation. https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/move-support-resources#app-service-domain
Since domain registration is billed differently and not tied to runtime costs, you can keep the domain as-is under the old subscription, while pointing DNS records (like A, TXT, CNAME) to resources in your new subscription.
- You can fully manage DNS from the App Service Domain's DNS zone (hosted in Azure DNS) or by linking a custom DNS zone in the new subscription. Manage App Service Domains
Or keep the domain in the old subscription, even after it expires Azure won’t delete App Service Domains just because the subscription is inactive, but you may lose the ability to renew it or manage it fully.
Raise a support ticket with Microsoft and request a manual reassignment of the domain to a new billing owner (shopper ID) tied to the 'Betalen na gebruik' subscription. https://ms.portal.azure.com/#view/Microsoft_Azure_Support/HelpAndSupportBlade/~/overview
Hope this information is helpful, if you have any further updates on this issue, please feel free to post back.