Microsoft 365 keeps buffering when you try to open Word, Excel, Outlook, or another app and the screen stalls on a loading spinner, white page, or endless “working on it” message. The problem is frustrating because the apps look installed and your files are there, but the Microsoft 365 service, cache, or network connection is blocking the app from finishing its start-up. This guide shows you the fastest fix first, then walks you through the exact steps to get Microsoft 365 loading normally again.
Quick fix
The single most effective fix is to sign out of Microsoft 365, quit every Office app, and start over with a fresh sign-in. If the buffering is caused by a stuck session token or a bad cached login, that clears it immediately. After that, restart your device and open one app first, such as Word, before launching the rest.
Why this happens
Microsoft 365 buffering is almost always a sign that the app cannot finish loading its online sign-in, license check, or cloud-synced content. A broken cache, stale credentials, an add-in hanging at startup, or a network filter blocking Microsoft services can keep the app stuck in a loading loop. In some cases, the desktop app is waiting on OneDrive, SharePoint, or Exchange data and never gets a clean response.
How to fix it
-
Quit every Microsoft 365 app completely.
Close Word, Excel, PowerPoint, Outlook, OneNote, and Teams. On Windows, press Ctrl+Shift+Esc, open Task Manager, and end any Microsoft Office or Office-related processes. On Mac, press Option+Command+Esc and force quit the apps. This matters because one frozen background process can keep the next launch stuck on buffering. -
Sign out of Microsoft 365 and sign back in.
Open Word or Excel, go to File > Account, and click Sign out under your account name. Close the app, reopen it, and sign in again with the same work or personal account. If the app never reaches the account screen, you are dealing with a local startup issue, not just an account refresh. -
Clear the Office sign-in cache.
On Windows, open Control Panel > Credential Manager > Windows Credentials and remove entries that mention MicrosoftOffice, ADAL, or your work account. Then restart the computer and open Microsoft 365 again. This forces the apps to rebuild their authentication data instead of reusing a corrupted token. If you use Mac, remove saved Microsoft entries from Keychain Access and then reopen the app. -
Disable add-ins that stall the app.
Open Word or Excel in Safe Mode by holding Ctrl while launching the app on Windows, then choose Yes when prompted. Go to File > Options > Add-ins, set Manage to COM Add-ins, click Go, and clear every box. Restart the app normally. If Microsoft 365 opens fast in Safe Mode, one add-in is the cause and you can turn them back on one at a time to identify the blocker. -
Repair Microsoft 365.
On Windows, open Settings > Apps > Installed apps, find Microsoft 365, click the three dots, and choose Modify or Change. Run Quick Repair first, then restart and test the app. If buffering continues, run Online Repair, which replaces damaged program files and refreshes the desktop installation. This is the right move when the app is installed correctly but a core file is damaged. -
Check the network path that Office depends on.
Open a browser and sign in to office.com. If the website also stalls, disconnect any VPN, pause third-party antivirus web protection, and try again on a different network. Then open Microsoft 365 after rebooting the router. If the browser works but the desktop app does not, the problem is local to the Office installation or its cached data, not your internet connection.
Common error messages
“Microsoft 365 is taking longer than expected to open”
This means the app launched but got stuck during sign-in, license verification, or cloud content loading.
“Working on it…”
This is the classic Office startup hang, and it points to a blocked cache, add-in, or background service.
“Something went wrong and your account wasn’t set up on this device”
This means the app cannot complete account authentication and needs the saved credentials cleared and rebuilt.
“If you keep seeing this message, restart your app”
This means the desktop client cannot finish a startup step and needs a full repair or cache reset rather than another click.
When this means it’s a bigger problem
If Microsoft 365 still buffers after a clean sign-out, a Safe Mode launch, a repair, and a test on a different network, the problem is beyond a normal desktop fix. That pattern points to a corrupted user profile, a device policy blocking Office services, or a tenant-side sign-in problem on a work account. If the same buffering happens on a fresh user account or a different computer with the same login, contact official Microsoft support or your organization’s IT team.
Helpful answers
Frequently Asked Questions
How long should Microsoft 365 take to stop buffering after I sign out and sign back in?
The change should be immediate. If Microsoft 365 is fixed by a fresh sign-in, Word, Excel, or Outlook opens normally as soon as you relaunch it. If the spinner stays stuck after a restart, the problem is not a simple session refresh and you need to move to cache, add-in, or repair troubleshooting.
Will repairing Microsoft 365 delete my files or settings?
No. Quick Repair and Online Repair rebuild the Microsoft 365 app files without deleting your documents, mail, or cloud data. Your account and files stay intact. The main thing you can lose is a custom startup preference or add-in state that gets reset when the app is repaired, which is the intended effect.
What should you do if Microsoft 365 still buffers after Quick Repair?
Run Online Repair next, then test Microsoft 365 again before changing anything else. If it still hangs, the issue is outside the basic app files and you should check for a blocked account, corrupted credentials, or a network filter. For deeper account-side cleanup, see Microsoft 365 Sign-In Problems.
Can you open Microsoft 365 on a different network to prove the problem is local?
Yes, and that test is decisive. If Microsoft 365 opens on a mobile hotspot or another Wi-Fi network, your original connection, VPN, DNS filter, or security tool is blocking Microsoft services. If it buffers on every network, the issue is local to the device, profile, or Microsoft 365 installation.
How do you undo the add-in changes after Safe Mode testing?
Reopen Word or Excel normally, go back to File > Options > Add-ins, and re-enable the COM Add-ins you cleared. Turn them on one at a time, then restart the app after each change so you can catch the one that causes buffering. If you want a cleaner reset path, repair Microsoft 365 instead of leaving add-ins disabled.