Azure App Service Certificate sync fails with BadRequest, and Support Request page is blank

Verify and restore the App Service Certificate’s Key Vault access, then run Sync—not Rekey—because the renewed certificate order and the linked private certificate are separate resources and renewal propagation depends on Key Vault access.^1^

1. Repair the certificate synchronization path

1. Open Azure portal → App Service Certificates → your certificate → Certificate Configuration → Step 1: Store.
2. Confirm that the Key Vault has a green checkmark and is in the same subscription and resource group as the certificate.
3. Check the vault’s permission model under Key Vault → Access configuration:

If it uses Vault access policy:

Under Access policies, verify these service principals and permissions:

• Microsoft.Azure.WebSites: Secret: Get, Certificate: Get
• Microsoft.Azure.CertificateRegistration: Secret: Get, List, Delete

Restore any missing entries and save.

If it uses Azure RBAC:

Assign the documented roles at the Key Vault scope. Replace the placeholders, but retain the service-principal IDs:

VAULT_SCOPE="/subscriptions/[Subscription ID] ID]/resourceGroups/[Resource Group] Group]/providers/Microsoft.KeyVault/vaults/<vault>"

az role assignment create \
  --role "Key Vault Secrets Officer" \
  --assignee "f3c21649-0979-4721-ac85-b0216b2cf413" \
  --scope "$VAULT_SCOPE"

az role assignment create \
  --role "Key Vault Certificate User" \
  --assignee "abfa0a7c-a6b6-4736-8310-5855508787cd" \
  --scope "$VAULT_SCOPE"

These role assignments require permission to create role assignments, which the subscription Owner normally has.^1^

4. Under Key Vault → Networking, check whether a firewall, service endpoint, or private endpoint blocks the App Service certificate backend. Where that networking model applies, enable access for trusted Microsoft services.
5. Do not delete or replace the vault or remove its AppServiceCertificateLock.
6. Return to App Service Certificate → Rekey and Sync → Sync. Do not select Rekey; Sync updates linked certificates and bindings with the current certificate.
7. If Sync completes but the app still has the old private certificate, open App Service → TLS/SSL settings → Private Key Certificates (.pfx) → Import App Service Certificate, import the renewed certificate, and update the custom-domain TLS binding.
8. Verify the certificate presented by the HTTPS endpoint, not only the date displayed on the certificate-order blade.

Since domain verification already succeeded, repeating DNS/domain verification is unnecessary.

2. If the same BadRequest remains

Microsoft’s certificate troubleshooting documentation does not identify this exact entity-name error. If Key Vault status, permissions, networking, and bindings are healthy, capture the following for support rather than deleting and recreating certificate resources:

• UTC timestamp of a failed Sync
• Certificate-order resource ID and linked Microsoft.Web/certificates resource ID
• Key Vault name and permission model
• Old and renewed thumbprints and expiration dates
• Full error text, correlation/request ID, and failed operation from the resource group’s Activity log
• Browser network trace or HAR file from the failed request, with credentials and tokens removed

3. Open a private support request despite the blank page

Because incognito mode, waiting, and multiple entry points have already failed, do not repeat those browser checks.

If the blank page is the Recommended solution/Solutions step, look for Return to support request, select it, and then select Next. This specific workaround has resolved the same blank Solutions-screen behavior.^2^ Complete Additional details → Review + create, and attach the sanitized trace and operation details. Microsoft’s documented workflow explicitly provides Return to support request after recommended solutions.^3^

Your Owner role is sufficient to create a portal support request, but technical support requires an eligible support plan; an active Azure Sponsorship subscription alone does not establish technical-support entitlement. Subscription-management and billing support remain available without a technical plan.^3^

If the entire blade remains blank and Return to support request is unavailable, use the Azure Support REST API, Azure CLI, or Az.Support PowerShell module as an advanced non-portal route.^4^ The documented REST technical-ticket prerequisites are narrower: an Azure subscription, Professional Direct, Premier, or Unified support, and Support Request Contributor at subscription scope. Verify those requirements before investing time in API submission; as Owner, you can assign Support Request Contributor if needed. The API requires retrieving the current service and problem-classification IDs rather than hard-coding them.

If your plan is not eligible for a technical case, submit a Subscription management request about the unusable support workflow, describe the certificate-expiration risk, and ask for routing assistance.

References

1. Troubleshoot Azure App Service certificates - Azure | Microsoft Learn
2. my support request is blocked from being created - Microsoft Q&A
3. Create an Azure support request
4. Azure Support REST API Reference