Outlook Keeps Asking for Your Password? Causes and Fixes

First: is it a glitch or someone else trying to sign in?

Before fixing Outlook, rule out the serious cause. A password box inside Outlook is normally just Outlook failing to refresh its sign-in. An MFA notification on your phone asking you to approve a sign-in you didn't start is different: it means someone typed your correct password somewhere else.

Fix 1: check the password in Outlook on the web

Open outlook.office.com in a private browser window and sign in with the same email address. If it works, your password and account are fine and the problem is on the computer. If it fails, Outlook can't fix it: the password may have expired or been changed, or the admin may have blocked the account or required a reset.

Also check that you're typing the full email address as the username, and that Caps Lock is off. It sounds basic, but a mistyped saved username produces exactly the same endless prompt.

Fix 2: clear saved credentials and update Office

Old saved sign-ins in Windows are the most common cause. Removing them forces Outlook to sign in fresh with modern authentication.

1. 1

   Close Outlook and every Office app

   Including Teams if it's signed in with the same account.

2. 2

   Open Credential Manager

   Search Windows for Credential Manager and choose Windows Credentials.

3. 3

   Remove Outlook and Office entries

   Remove entries that mention Outlook, MicrosoftOffice or your email address. Leave unrelated entries alone.

4. 4

   Check the work account in Windows

   In Settings, Accounts, Access work or school, check your work account is listed and not showing an error. Don't disconnect it on a company-joined laptop without asking your admin.

5. 5

   Update Office

   Open Word, go to File, Account, Update Options, Update Now, then restart the computer.

6. 6

   Open Outlook and sign in once

   Complete the Microsoft sign-in window and MFA. It should then stay quiet until your sign-in expires.

If you still see the old-style grey password box rather than the Microsoft sign-in window, Outlook isn't using modern authentication. Microsoft's modern authentication article describes a registry setting that forces it for Autodiscover in mixed or migrated setups; that's a job for whoever manages your PCs.

Fix 3: create a new Outlook profile

If the prompts continue, the Outlook profile itself may be damaged, often after a mailbox migration. A new profile re-runs Autodiscover and sign-in from scratch. Your mail lives in Microsoft 365, so nothing is lost, but the first sync can take a while on a large mailbox.

• Close Outlook, open Control Panel, then Mail, then Show Profiles.
• Click Add, name the profile, and add your work email account.
• Choose 'Always use this profile' and select the new one, then open Outlook.
• Re-add any shared mailboxes or calendars that were added by hand.

Microsoft's continual prompts article also offers a self-diagnostic, 'Diag: Outlook keeps asking for my password', for newer Outlook builds connected to Exchange Online.

Old Office versions and modern authentication

Microsoft's Office connectivity page lists which versions are supported for connecting to Microsoft 365 services. Older versions may still connect, but Microsoft says they can hit unexpected reliability issues, and repeated password prompts are a typical symptom.

If staff are on a one-off Office purchase, the lasting fix is usually moving them to the Microsoft 365 Apps that come with Business Standard or Premium. If you're also deciding between new and classic Outlook, see our new vs classic Outlook guide.

Security changes that cause new prompts

Prompts often start the day an admin tightens security, which is a good thing. Microsoft's security defaults page says turning them on requires every user to register for MFA, blocks legacy authentication protocols and blocks device code flow. Since 29 July 2024 there is no 14-day grace period for registration.

So after security defaults or Conditional Access are switched on, users must complete MFA registration once, and old apps that only support basic authentication stop working. That includes some scanners and older email apps; our scan-to-email guide covers devices that stop sending. If your admin set a sign-in frequency policy, Outlook will ask you to sign in again at that interval by design.

Do it yourself or get help?

Most cases are fixed by clearing Credential Manager, updating Office or creating a new profile, which you can do in 15 minutes. Get help if prompts affect several people at once, if you see MFA requests you didn't start, or if staff are on unsupported Office versions.

Our Quick Fix (1 hour) (S$119) covers a remote session to find and fix the cause on one or more PCs, including checking sign-in logs for anything suspicious.