Sign-in & Login Problems

How to Fix All Users Cannot Sign In to Microsoft 365 School Tenant

Amos Gikunda Sep 25, 2026 870 views

Question details

A widespread login failure where no users within an entire Microsoft 365 educational tenant are able to access their accounts or services.

How to Fix All Users Cannot Sign In to Microsoft 365 School Tenant

Product: Microsoft 365
Device & OS: not provided
Scenario: A school administrator discovers that every student and staff member in their Microsoft 365 tenant is suddenly blocked or unable to sign in.
Observed behavior: All users across the organization experience sign-in rejections or errors, completely preventing access to emails, documents, and cloud services.

Before you start

Gather specific details about the outage, including the exact sign-in error messages, the time the problem started, and the affected domain names. Ensure you have the tenant administrator credentials ready to check system health.

Solution 1Recommended

Check Microsoft 365 Service Health and Active Subscriptions

Determine if the issue is caused by a global Microsoft service outage or an expired educational subscription by logging into the admin center.

When an entire tenant is locked out, the root cause is typically a Microsoft service degradation, an expired billing subscription, or a global conditional access policy error.

Attempt Admin Login

Try to sign into the Microsoft 365 admin center (admin.microsoft.com) using a global administrator account. If successful, you can diagnose the tenant-wide issue.

Check Service Health

Navigate to the 'Health' section in the left sidebar and click 'Service health'. Look for any ongoing incidents affecting Entra ID (formerly Azure AD) or Exchange Online.

Verify Education Licenses

Go to 'Billing' and then 'Your products'. Check if your Office 365 A (Education) subscriptions are active, unexpired, and successfully assigned to your users.

Check Microsoft 365 Service Health and Active Subscriptions

Global Outages: If a service incident is listed in the service health dashboard, you must wait for Microsoft engineers to resolve the backend issue globally. Local fixes will not work.

Solution 2

Contact Microsoft Data Protection Support

Use this method if the global administrators are also locked out of the tenant and cannot access the admin center to investigate.

Free Microsoft Office alternative

Need a Reliable Offline Alternative for Your School? Try WPS Office

Microsoft 365 tenant lockouts can disrupt entire school days if users rely solely on cloud authentication. Consider WPS Office as a free, lightweight, and highly compatible desktop alternative that lets students and teachers create, edit, and save documents locally without tenant sign-in hurdles.

1. Download the Software: Visit the official WPS Office website and download the free desktop application.
2. Install WPS Office: Run the installer and follow the on-screen prompts to set up the software in minutes.
3. Open Office Files Instantly: Double-click your existing Microsoft Word, Excel, or PowerPoint files to open and edit them without needing complex tenant authentication.

Completely free for basic student, teacher, and administrative usage.Fully compatible with Microsoft Office formats including .docx, .xlsx, and .pptx.Works perfectly offline, ensuring document access even during cloud service outages.Lightweight software with a familiar, easy-to-learn user interface.

microsoft office alternative - wps office

Frequently Asked Questions

Why is my Microsoft 365 school tenant suddenly blocking all users?

This usually happens due to an expired educational license (such as Office 365 A1/A3), a widespread Microsoft Entra ID authentication outage, or an incorrectly configured conditional access policy locking out the entire organization.

How can I fix the login issue if the admin account is also locked out?

If no global administrator can log in, you cannot fix it through the admin portal. You must contact Microsoft Data Protection support by phone, provide your tenant details, and verify your identity to regain access.

Can an unassigned Copilot license cause sign-in failures for all users?

No, an unassigned Copilot license will only restrict access to specific AI features. A tenant-wide sign-in failure points to a core authentication issue, domain suspension, or an expired primary Office 365 A license.

Login & Account Issues