Microsoft 365 Error Codes

Fix Microsoft 365 Sign-In Error 120018: Causes and Solutions

Olivia Miller Oct 13, 2026 869 views

Question details

The user is unable to log in to Microsoft 365 and encounters error code 120018, which is accompanied by a Request ID, Correlation ID, and Timestamp.

How to Fix Microsoft 365 Sign-In Error 120018

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to sign in to Microsoft 365, typically using a newly assigned school or work account.
Observed behavior: The authentication process fails, displaying error code 120018 instead of granting access to the Microsoft 365 dashboard.

Before you start

Before troubleshooting, ensure you are connected to a stable internet network and have your exact Microsoft 365 organization email address and password ready.

Solution 1Recommended

Verify Account Details and Use a Private Browser

This solution helps rule out cached browser credentials and ensures you are using the correct organizational account type.

Error 120018 frequently occurs when users attempt to log in with a personal account on an enterprise portal, or when cached browser data conflicts with a new school or work account sign-in.

Confirm account status

Check with your school or organization to ensure your account has been fully provisioned and is active.

Open a private browsing window

Launch your web browser and open an Incognito or Private browsing session to bypass any previously saved Microsoft credentials.

Sign in with the correct account

Navigate to the Microsoft 365 login page and enter your designated work or school account details, ensuring you do not use a personal Microsoft account.

Verify Account Details and Use a Private Browser

Account Provisioning Delay: If your school just created the account, it may take up to 24 hours for the account to propagate across all Microsoft 365 services.

Solution 2

Report the Error IDs to Your IT Administrator

If basic troubleshooting fails, your tenant administrator must investigate the issue from the Microsoft 365 Admin Center.

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Frequently Asked Questions

What does Microsoft 365 error 120018 mean?

Error 120018 usually indicates an authentication issue with a work, school, or tenant account. It means the system could not validate your credentials, often because the account has not been fully created yet, is currently inactive, or you are trying to log in with a personal account instead of an organizational one.

Why are the Request ID and Correlation ID important?

These IDs act as unique identifiers for your specific sign-in attempt. Microsoft Support and your IT administrator use them to track the exact authentication event in their system logs, allowing them to pinpoint the exact server-side cause of the failure.

Can I fix error 120018 by simply resetting my password?

If the issue is caused by entering an incorrect password, resetting it might help. However, if the account is not yet active or blocked at the administrative level, a password reset will not resolve the error. You will need to contact your IT administrator for further assistance.