Another Account Is Already Signed In On This Device | Fix

You’ll see this when an app detects saved sign-in tokens for one account, then you try to log in with another. The app treats that mix as a conflict and stops the login flow.

Most fixes are simple. The trick is choosing the right reset level.

What This Message Usually Means

This error is rarely about your password. In most cases, the app is reacting to stored account data on the device. That data can live inside the app, inside your browser profile, or inside the operating system’s account store.

These patterns show up a lot:

• Saved Tokens Collide — One account’s sign-in tokens are still present, so the app won’t accept a different account until the old tokens are removed.
• Work Or School Device Binding — Some organizations limit sign-in so one managed account stays tied to the device for licensing or device registration.
• Browser Session Mix-Up — A web login is pulling cookies from a different profile or a private window, so the wrong account keeps “winning” the session.
• Partial Sign-Out — You signed out in one place, but another component stayed signed in, like a background service or shared credential store.

This table helps you pick a starting point without guessing.

Checks That Solve It Without Resetting Anything

Before you wipe data, try these checks. They fix many cases and keep your device settings intact.

1. Close Every Related App — Quit the app you’re signing into and any companion apps that share the same login, then reopen only the one you need.
2. Restart The Device — A restart clears stuck background sign-in processes that don’t exit cleanly.
3. Confirm The Account You Want — If you’re switching between work accounts, sign out of the old one across apps on that device first.
4. Check Date And Time — Set time to automatic. Tokens can fail when the clock is off.
5. Update The App — Install pending updates for the app that shows the message, then try again.
6. Try A Clean Browser Session — On web logins, use a separate browser profile, or use a private window and sign in with the intended account.

This is usually enough.

If the message shows up, pick the section below that matches where you see it. The steps are grouped from light to heavy.

Another Account Is Already Signed In On This Device

This section targets the exact message inside Microsoft 365 apps. Microsoft documents a closely related activation error where another organizational account is already signed in, even when you don’t see any other account on screen.

Windows Steps For Microsoft 365 Apps

1. Sign Out Of All Office Apps — Open Word or Excel, open the account screen, sign out of every listed account, then close all Office apps.
2. Restart And Sign In Once — Restart Windows, open one Office app, then sign in with only the account you want to use.
3. Clear Office Sign-In Cache Folders — If it still fails, close all Office apps and delete the contents of these folders, then restart and sign in again:
   • OneAuth Folder — %localappdata%\Microsoft\OneAuth
   • IdentityCache Folder — %localappdata%\Microsoft\IdentityCache
4. Disconnect Work Or School Access — Open Settings > Accounts > Access work or school, disconnect accounts you no longer use on this Windows profile, then restart.
5. Update Windows And Office — Install Windows updates, then update Office from File > Account > Update options.

Mac Steps For Microsoft 365 Apps

1. Close All Microsoft 365 Apps — Quit Word, Excel, Outlook, Teams, and OneDrive if they’re open.
2. Reset OneAuth Credentials — Open Terminal and run this command, then reopen Word and try activation again:

   defaults write com.microsoft.Word ResetOneAuthCreds -bool YES

3. Restart Then Try Again — Restart the Mac, then sign in with one account inside one Office app first.

If this is a managed work or school account, device rules can block certain account switches. When that happens, a new user profile on the device can separate old tokens from the new sign-in.

Account Already Signed In On This Device On Android And iPhone

On phones, this message often means the account is already present at the operating system level, or the app has stale login data after a device transfer. The fix is usually a full sign-out and re-add.

Android Fixes That Work In Most Apps

1. Remove The Account From Android — Go to Settings > Passwords & accounts (or Accounts), pick the account, and remove it from the device.
2. Clear App Storage — Go to Settings > Apps > the affected app > Storage, then clear cache and clear storage.
3. Add The Account Back — Return to Accounts and add the account again, then sign in inside the app.
4. Reinstall The App — Uninstall, restart the phone, then reinstall and try signing in.

iPhone And iPad Fixes

1. Sign Out Inside The App — If the app still opens, sign out from its settings screen and close the app.
2. Delete And Reinstall — Delete the app, restart the device, then install it again from the App Store.
3. Remove Stored Login Items — If the app uses saved passwords, remove the saved entry in iOS Passwords, then try signing in again.

If you see the exact text another account is already signed in on this device right after you enter your email, it often means the device is auto-picking a different saved account. A full removal plus re-add usually stops that auto-pick.

Deep Reset For Stuck Sign-In Data On Windows And Mac

If the light fixes didn’t work, you’re probably dealing with a credential store that’s out of sync. These steps are more invasive, so use them only when the message blocks access.

Windows Credential Store And Broker Fixes

1. Clear Token Broker Account Files — If Microsoft sign-in is stuck across apps, delete account files in these folders, then restart Windows:
   • BrokerPlugin Accounts — %LOCALAPPDATA%\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\AC\TokenBroker\Accounts
   • CloudExperienceHost Accounts — %LOCALAPPDATA%\Packages\Microsoft.Windows.CloudExperienceHost_cw5n1h2txyewy\AC\TokenBroker\Accounts
2. Pause VPN And Filtering — If your connection runs through VPN or security filtering, disable it briefly and retry the sign-in flow.
3. Create A New Windows User Profile — A fresh local profile gives Office and browsers a clean sign-in store when the current profile is tangled.

Mac Cleanup When Office Still Won’t Switch Accounts

1. Remove Extra Office Accounts — Open an Office app, open the account screen, and sign out any account you don’t use.
2. Restart After Reset — After running the ResetOneAuthCreds command, restart the Mac before you try a fresh sign-in.

After a deep reset, sign in to one app first, confirm it works, then add the rest. That pacing keeps new tokens from mixing again.

Keep It From Coming Back After You Fix It

Once the login works again, a few habits prevent repeat conflicts, especially on shared devices that rotate between personal and work accounts.

1. Use Separate Browser Profiles — Keep work accounts in one browser profile and personal accounts in another. This separation stops cookie collisions.
2. Pick One Primary Account Per App — If an app ties itself to one account, avoid switching accounts inside it. Use a second device or a second profile when you need both.
3. Sign Out Of Old Sessions — Review account sessions and devices in your account security pages, then sign out of sessions you no longer use.
4. Change Password After Suspicious Activity — If you don’t recognize a device or a session, change your password and turn on two-step verification.
5. Disable Stay Signed In On Shared Devices — Turn off “stay signed in” where the app allows it, so a family member doesn’t inherit your session.

If you’re still stuck after the steps above, the error can be enforced by a work or school policy at the tenant level. In that case, the fix is administrative, not on the device.

Use this test to narrow it down. If you can sign in on another device with the same account, but every app on this device fails with the same message, the device’s stored tokens are still the bottleneck. If only one app fails, reset that app first.

One last note: when you see another account is already signed in on this device in a Microsoft 365 app, it can be a cached identity from a different sign-in attempt on the same user profile. Clearing the sign-in stores and signing in once is usually the cleanest path.

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