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Mandatory MFA for the Microsoft 365 admin centre: what breaks, and the fix for each

Microsoft now requires a second factor to reach its administrative portals. Right, and also how tenants discover the six-year-old script that runs as a user. The five things that break, and the order to fix them in.

By Alex Makey · 6 September 2026 · 7 min read · Verified against Microsoft documentation, September 2026

Microsoft has been enforcing multi-factor authentication for administrative portals in stages, and by 2026 the enforcement reaches the Microsoft 365 admin centre itself: sign in without MFA and you do not get in. This is right, and it is also how a surprising number of tenants discover the service account that has been running a nightly job for six years. Here is what changes, what breaks, and what to do about each.

What is enforced

Sign-in to the Azure portal, the Entra admin centre, the Intune admin centre and the Microsoft 365 admin centre requires a second factor, regardless of Conditional Access and regardless of security defaults. Microsoft applies it at the service; you cannot opt out, only postpone within the window Microsoft allowed, and that window has been closing through 2025 and 2026.

It applies to every account that signs in to those portals, including accounts that are not administrators but happen to visit. It applies to break-glass accounts. It applies to the account the reseller uses under delegated administration.

What breaks

Scripts and automation that sign in as a user. A PowerShell job running under a named account with a stored password, connecting to Exchange Online or Graph. It has no way to complete MFA and it stops. These are usually the oldest, least documented processes in the tenant.

Shared administrator accounts. One account, one password, four people. MFA needs a second factor that belongs to a person; a shared phone in a drawer is the failure mode.

Break-glass accounts with no second factor. Excluded from Conditional Access by design, and therefore never registered. They now need one, and it should not be a phone.

Partner and reseller access where the partner’s staff have not enrolled.

Users who never registered because they never needed to. The first time they are prompted is when they need in urgently.

The fix for each

Automation: move it off user accounts. Register an application in Entra ID, grant it the specific Graph or Exchange permissions the job needs, authenticate with a certificate rather than a secret, and run the job as the application. For Exchange Online this is app-only authentication with a certificate; for Graph it is client credentials. This is more work than the rest of the list combined and it is the one that matters, because a job that stops silently is a job nobody notices until the report is missing.

Shared administrator accounts: retire them. One person, one account, one role. Where a shared account is genuinely needed — a vendor, a helpdesk — use Privileged Identity Management to grant the role just in time to a named person instead.

Break-glass: a FIDO2 security key per account, stored with the password. Not SMS, not an authenticator app on someone’s phone. The full setup is here.

Partner access: ask. A partner that has not enrolled its own staff in MFA is telling you something.

Everyone else: a registration campaign before the deadline, not after. Entra ID has one built in — it nudges users to register the Authenticator app at sign-in over a period of weeks, so nobody meets the requirement for the first time on a Monday morning.

The order

1 — InventorySign-in logs: every account that reaches an admin portal, and every non-interactive sign-in by a user account
2 — Automation firstMove each job to an app registration with certificate auth; test; retire the user account
3 — Break-glassFIDO2 keys registered and tested
4 — AdministratorsPhishing-resistant method where possible; Authenticator at minimum
5 — Registration campaignEveryone else, over weeks
6 — VerifyReport: accounts with no registered method; chase to zero

What this is not

It is not a reason to disable Conditional Access or security defaults, which do more than portal MFA. It is not satisfied by SMS, which Microsoft is steadily retiring as a method. And it is not optional: an administrator who has not registered a method by the enforcement date is locked out of the portal until they do, and can only register by signing in — which is the loop that ends in a support ticket.

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Related questions

Asked most often

Is MFA now mandatory for the Microsoft 365 admin centre?

Yes. Microsoft has enforced multi-factor authentication for its administrative portals in stages, reaching the Microsoft 365 admin centre in 2026. It applies at the service, regardless of Conditional Access, to every account that signs in to those portals.

What breaks when Microsoft enforces MFA for administrators?

Scripts running under user accounts with stored passwords, shared administrator accounts, break-glass accounts with no second factor, partner staff who have not enrolled, and users who never registered a method.

How do I keep PowerShell automation working with mandatory MFA?

Move it off user accounts. Register an application in Entra ID with the specific permissions the job needs, authenticate with a certificate, and run the job as the application using app-only authentication.

What second factor should a break-glass account use?

A FIDO2 security key stored with the password. Not SMS and not an authenticator app on someone’s personal phone. The key satisfies MFA without depending on Conditional Access.

Can I opt out of mandatory admin MFA?

No. Microsoft allowed postponement within a window that has been closing through 2025 and 2026. After the enforcement date an account without a registered method cannot sign in to the portal.

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