Microsoft outlook keeps prompting to sign in

If Outlook keeps asking you to sign in, first check whether it happens in one app, on one device, or everywhere; that split usually shows where the fault sits. The quickest first check is the account type and password status inside Outlook itself. This guide separates account, device, and server causes across Windows, Mac, iPhone, iPad, Android, and the web.

Outlook sign-in matrix

What the sign-in loop means

The loop usually means Outlook can reach your mailbox, but it cannot keep a valid sign-in token for long. If the prompt appears on every device, think account or server first. If it appears on one device only, start with cached credentials, app state, or profile data on that device.

Say your Windows laptop opens Outlook 2019, shows a sign-in box, and returns to the mailbox after you click Cancel, only to ask again five minutes later. That pattern points to saved credentials or Autodiscover, not a simple typo in the password.

Likely causes, ranked

1. Stale saved credentials or token data on the device
2. Password change or expired password that Outlook has not picked up
3. MFA reauth that the app has not completed cleanly
4. Wrong account type selected in Outlook
5. Autodiscover or profile corruption for a Microsoft 365 mailbox
6. Server-side auth or mailbox policy issue that needs admin help

Check the account type first

Outlook sign-in can use either a personal Microsoft account or a work or school Microsoft 365 account, and many people have both. A mismatch here can send you in circles even when the password is correct. If the wrong account is active, the prompt can repeat forever.

1. In Outlook on Windows, open File > Account or Office Account.
2. Check which account is signed in and whether it matches the mailbox you expect.
3. On iPhone or iPad, open the Account screen and tap Sign In.
4. Sign out of the wrong account, then sign in with the correct Microsoft account or work/school account.
5. If you see more than one account, choose the one tied to the mailbox that keeps prompting.

For a work mailbox, the Microsoft 365 account may be required even if the same person also uses a personal Microsoft account for Office at home. Keep those sign-ins separate.

Clear cached credentials and tokens

Cached Outlook or Office passwords in Windows Credential Manager are a common cause of repeated prompts. Stale entries can keep feeding Outlook old sign-in data after a password change or device update. On mobile, the same issue shows up as a stale account token in the app.

1. Close Outlook and all Office apps.
2. Open Control Panel > Credential Manager > Windows Credentials.
3. Remove saved entries that mention Outlook, Office, MicrosoftOffice, or your email address.
4. Restart Windows, then open Outlook and sign in again.
5. If the prompt is on iPhone or iPad, remove the account from Outlook, then add it back from the Account screen.

Some users stop at the first prompt and keep clicking Cancel. That only hides the issue for a moment. The stale token still asks again later.

Fix password and MFA reauth prompts

If the password was changed recently, Outlook may still hold the old one. MFA can also trigger repeated prompts if the app needs a new approval and never stores the refreshed token. This often follows security policy changes or device resets.

1. Open Outlook and enter the current password when prompted.
2. In Windows Outlook, go to File > Account and confirm the correct account is selected.
3. If the password was changed elsewhere, update it in Outlook before trying other fixes.
4. Complete the MFA prompt fully, including any app approval or code entry.
5. If the prompt keeps returning, sign out of Office apps, restart, then sign in again with the current password and MFA approval.

If the mailbox is a Microsoft 365 work account and the password is valid everywhere except Outlook, ask whether the admin recently changed sign-in policy or required a fresh MFA registration.

Could Autodiscover be causing the loop?

Autodiscover helps Outlook find mailbox settings for Microsoft 365 accounts and some Exchange setups. If that discovery path is wrong, Outlook can keep checking the server and asking for sign-in again. This matters most for cloud mailboxes, but on-premises Exchange can also be involved.

1. Test the mailbox in Outlook on the web. If webmail works, the account itself is often reachable.
2. In desktop Outlook, create a new profile if the prompt appears only in one profile.
3. Check whether the mailbox is an Office 365 / Microsoft 365 mailbox or an on-premises Exchange mailbox.
4. If the mailbox is cloud-based, remove the old profile and create a new one so Outlook rebuilds its connection data.
5. If the issue affects only one organization account, ask the Microsoft 365 admin to review Autodiscover and sign-in policy.

For a cloud mailbox, repeated discovery checks can look like random password prompts. They are not random. They usually mean Outlook cannot settle on a stable sign-in path.

Why does Outlook keep asking you to sign in on iPhone?

On iPhone and iPad, the loop usually points to the app’s saved account state, an expired token, or a sign-in that never finished cleanly. Start by opening Outlook, going to the Account screen, and tapping Sign In before deleting the app. If the prompt repeats, refresh the account instead of guessing at password settings. (Microsoft Support)

1. Open Outlook for iOS or iPadOS and go to the Account screen.
2. Tap Sign In and choose the correct Microsoft account or work/school account.
3. Approve MFA if it appears.
4. Update the app and iOS or iPadOS if prompts keep returning.
5. If the loop continues, remove the account from Outlook, then add it back.

Suppose an iPad keeps asking for the work mailbox password after every app switch, while the same mailbox works in the web app. That points to stale mobile sign-in data, not a broken mailbox.

Still not working?

If Outlook still loops after the account check, credential cleanup, and profile repair, use Outlook on the web to separate a device issue from a mailbox issue. If webmail works everywhere else, the local Outlook profile or mobile token is the likely fault. If webmail also fails, the account or server needs attention.

1. Try the mailbox in Outlook on the web.
2. If webmail works, rebuild the Outlook profile on the affected device.
3. If the issue is a Microsoft 365 work account, contact the Microsoft 365 admin to check authentication policy, mailbox state, and Autodiscover.
4. If the issue affects a personal Microsoft account tied to Office, use Microsoft account recovery and sign-in help.
5. Escalate to Microsoft support if the prompt returns across devices and the account cannot stay signed in anywhere.

Prevention: after a password change, sign out of Office apps on the affected device, then sign back in once from the correct account screen. That reduces the chance of stale credentials lingering in Outlook and Office.

Frequently asked questions

Why does Outlook keep asking me to sign in?

Most often, Outlook keeps asking because the device has stale saved credentials, the password changed, or the app lost its sign-in token. Start with File > Account on Windows or the Account screen on iPhone and iPad, then remove old credentials if the prompt returns.

Why does Outlook keep asking me to sign in on iPhone?

On iPhone, the loop usually comes from a stale Outlook account token or a sign-in that did not finish cleanly. Open Outlook, use the Account screen, tap Sign In, complete MFA, and if the loop continues, remove and re-add the account.

Why do I have to sign into Microsoft Outlook every time?

If you sign in every launch, the app is usually failing to keep a valid token. Check for cached credentials in Windows Credential Manager, confirm the account type, and review whether MFA or password changes happened recently. A webmail test helps show whether the issue is local.

Why does Outlook keep asking to sign in after I change my password?

After a password change, Outlook may still hold the old password in saved credentials or an older profile. Enter the new password in Outlook, clear saved Outlook and Office entries in Windows Credential Manager, and restart the app before trying to reconnect again.

How do I stop Outlook from prompting for my password?

Use the correct account, remove saved credentials, and make sure the password stored in Outlook matches the current one. On Windows, check File > Account; on iPhone or iPad, use the Account screen. If prompts continue, repair the profile or re-add the account.

Why does Outlook keep prompting for Microsoft sign in on Windows?

On Windows, the most common causes are stale credentials, profile corruption, or an Autodiscover issue for a Microsoft 365 mailbox. Open File > Account, clear the saved entries in Credential Manager, and test Outlook on the web to see whether the mailbox itself is reachable.

Is this caused by cached credentials or account sync issues?

Yes, cached credentials are a common cause, especially on Windows. If Outlook accepts a password once but asks again later, clear saved Outlook and Office entries, then sign in from the correct account screen. On mobile, remove and re-add the account to refresh the token.

What should I check first if Outlook keeps looping back to the sign-in screen?

Check whether the issue happens on one device or every device. Then confirm the account type, verify the current password, and test Outlook on the web. That order separates a device problem from a Microsoft 365 account or server problem without wasting time on the wrong fix.