I was running through a routine cost review in the portal when I spotted a charge I didn't recognise. Azure Front Door Standard. £15, from 11 April to 30 April. Nineteen days. Resources I hadn't configured and wasn't actively using.
That works out to around £30 a month per profile. On resources sitting idle.
What happened
Microsoft has been retiring Azure CDN Standard from Microsoft (classic). The deadline for managed certificate renewal was 14 April 2026, and any classic profiles using CNAME-based domain validation needed to either migrate or set a feature flag by 9 April to opt out of automatic migration.
The email arrived. I didn't act on it in time.
On 10 April, Microsoft automatically migrated eligible classic profiles to Azure Front Door Standard. The billing changed immediately. CDN classic and Azure Front Door Standard use different pricing models, and the charges started from the migration date.
The pricing shift
Azure CDN classic charges primarily for bandwidth. Dormant or low-traffic profiles cost effectively nothing per month.
Azure Front Door Standard has a profile-level base cost regardless of traffic. A dormant profile that cost close to £0/month on CDN classic runs around £30/month on AFD Standard. Per profile, per site, before any traffic.
That's the number worth understanding. It's not a bandwidth charge. It's a standing cost for the profile existing.
The support ticket
The profiles in question had no active domains and no meaningful traffic. I raised a support ticket to request a credit on the basis the resources were dormant and the migration was automatic rather than deliberate.
If you're in the same position, that conversation is worth having.
What to check
In the Azure portal, go to Front Doors and filter by Pricing tier = Classic, Service type = Microsoft CDN. That shows any remaining classic profiles. If you've already been migrated, they'll appear as Standard or Premium.
Pull the cost in Cost Management filtered from 10 April onwards. Any profile showing AFD Standard charges with no meaningful traffic is either dormant or a candidate for deletion.
Deleting an unused profile stops the charges immediately.
The pattern
Classic CDN profiles accumulate over years. Test environments, proofs of concept, projects that shipped and were never fully decommissioned. Most teams don't audit them until something shows up on the bill.
The managed certificate cutoff accelerated what was always coming. The billing model changed in April. The full retirement deadline is September 2027, but the cost impact is already here.
If you want an independent review of your Azure estate, including dormant resources and unexpected charges, our free cost assessment starts with a read-only look at your cost data.