Troubleshooting Microsoft 365

Solutions to the most common Microsoft 365 problems — from sign-in issues and email not sending to OneDrive sync problems and app errors.

Something not working as expected in Microsoft 365? This guide covers the most common issues and how to fix them — in plain English, step by step.

Quick summary

Most Microsoft 365 problems fall into a few categories: sign-in and authentication issues, email problems, sync errors in OneDrive, and app errors. Start by checking the Microsoft service health page to see if there's a known outage. Then work through the relevant section below.

First: check if Microsoft is having a problem

Before troubleshooting your own setup, check whether Microsoft's services are experiencing an issue:

In the admin center: Go to admin.microsoft.com and select Health → Service health in the left-hand navigation, or use the Service health card on the Home dashboard.
If you can't sign in: Visit the public Microsoft service health status page. (The old status.office.com address redirects there.)

If there's a known outage affecting your service, the fix is to wait. Microsoft will resolve it and post updates. The Issue history tab in the admin center shows what has been resolved in the last 7 or 30 days, and if you're hitting something Microsoft hasn't listed, you can flag it with Report an issue.

Double-check the email address. It should be your work email (for example, you@yourcompany.com), not a personal Gmail or Hotmail address.
Ask your admin to confirm your account is active in Users → Active users.

"I forgot my password"

Enter your user name, select Next, then select Forgot password and follow the reset steps.
Resetting your own password only works if your admin has turned on self-service password reset. If it isn't set up, ask your admin to reset your password.

"I can't get through the multi-factor authentication step"

If you can't access your authenticator app, look on the sign-in screen for a link to a different verification method (text message, a second phone number, and so on).
If you're completely locked out, ask your admin: they can reset the verification methods on your account. See Turning on multi-factor authentication for admin steps.
Worth knowing: admins now have to use MFA to sign in to the admin centers, so "turn it off for me" isn't an option.

"I keep getting signed out"

When Microsoft asks "Stay signed in?", answer Yes. That's the setting that keeps you signed in on that browser. Without it, the sign-in lasts up to 24 hours, or until you close the browser. Don't do this on a shared computer.
Your organization may also have set shorter session limits through a Conditional Access policy — ask your admin if it keeps happening.
Check that your browser isn't blocking or clearing cookies from Microsoft's sites. Teams on the web also needs third-party cookies allowed for some add-in apps to work.

Email problems (Outlook)

"My emails aren't sending"

Check your internet connection.
Check if your mailbox is full. Once you're over quota you can't send or receive at all, and senders get an error saying your mailbox is full. See Storage & quotas.
Check the attachment size. Microsoft's default ceiling for a Microsoft 365 mailbox is 35 MB for sending, and your admin can set it anywhere from 1 MB to 150 MB. Put anything bigger in OneDrive and share a link instead.
If you're emailing a lot of people, note the cap of 10,000 recipients a day, and a per-message recipient limit your admin can set up to 1,000.
Check the Outbox folder — sometimes emails get stuck there. Try opening and resending.
If using the desktop app, try sending from the web version at outlook.office.com to see if the issue is with the app.

"I'm not receiving emails"

Check your Junk Email folder — emails may be going there incorrectly.
Check your inbox rules — a rule may be moving emails to a folder you haven't noticed.
Ask the sender to resend and check if they receive a bounce-back message.
If your domain was recently added to Microsoft 365, check that DNS / MX records are fully updated. See Adding a domain.

"Outlook is slow or crashing"

In the web version, try clearing your browser cache and refreshing.
In the desktop app on Windows, try Office Safe Mode, which starts Outlook with add-ins disabled: hold Ctrl and double-click the Outlook shortcut, then select Yes when it asks whether to start in Safe Mode. You can also press the Windows key + R, type outlook /safe and select OK. To leave Safe Mode, close Outlook and open it normally.
Check for pending Windows updates — outdated systems can cause app instability.

OneDrive sync problems

"Files aren't syncing"

Click the OneDrive icon in your notification area (Windows) or menu bar (Mac) to see the sync status. It may show a specific error message. A cloud icon with a red blocked symbol means your OneDrive is full.
Make sure you're signed in to OneDrive with the correct work account.
Pause and resume syncing: right-click that icon (Ctrl-click on a Mac) and choose how long to pause — 2, 8 or 24 hours. Syncing starts again on its own when the time is up, or you can resume it yourself.
If it's still stuck, select the OneDrive Help and Settings icon, choose Quit OneDrive, then open OneDrive again.
Check whether you're over quota. While you are, you can't upload, edit or sync new files and your existing files are read-only, so sync failures are expected. See Storage & quotas.
Very large synced libraries can misbehave. Microsoft's recommendation is to sync no more than 300,000 files in a single OneDrive or team site library.

"There's a sync conflict"

If two people edit the same file offline at the same time, the versions can clash. When the file syncs, you'll get an alert about the conflict — in Word you'll see a pop-up you can click through to sort it out. If you end up with two copies, open both, compare them, keep the one you want, and delete the other. OneDrive also keeps version history: right-click the file and select Version history to see and restore earlier versions.

Teams problems

"I can't join a meeting"

Check that your browser allows camera and microphone access for Teams.
Try a different browser — Edge or Chrome first. Microsoft supports Teams on the web in Microsoft Edge, Chrome, Firefox and Safari on a desktop computer, but for meetings specifically it names Edge and Chrome as fully supported and its pages disagree about how completely Firefox handles them. Teams on the web is not supported in a mobile browser at all, so on a phone or tablet you need the Teams app.
Ensure your internet connection is stable — Teams calls need a reasonable upload and download speed.

"My audio or video isn't working in a meeting"

Check your device settings in the meeting pre-join screen — make sure the right microphone and camera are selected.
Check that no other application is using your microphone or camera at the same time.

App errors

"I get an error saying my license has expired or isn't valid"

This usually means a license hasn't been assigned to your account, or the subscription has lapsed.
An admin should check your license status in Users → Active users, then check Billing → Your products to see if the subscription is active.

Try a different browser if things look broken

Many Microsoft 365 issues in the browser are caused by browser extensions, cached data, or compatibility problems. Try opening an incognito/private window or a different browser before spending time troubleshooting further.

Common questions

Where can I contact Microsoft 365 support directly?

Admins can open a support request from the admin center. Go to admin.microsoft.com, select Help & support at the bottom right of the page, and type your question into the Support Assistant. If the suggested answers don't help, select the Contact Support (headset) icon, then choose phone or email and confirm your contact details.

Two catches. You have to be an admin on a business subscription to use these methods. And if you bought all your subscriptions through a reseller rather than from Microsoft, Microsoft asks you to contact that partner for support instead. If either applies to you, come to us.

How do I know if the problem is on my computer or with Microsoft's servers?

Try accessing the same service on a different device or a different network. If it works on another device, the problem is likely with your computer or browser. If it fails everywhere, check the Microsoft service health page — it's likely a Microsoft outage.

I've tried everything. What do I do next?

Reach out to us at Chykalophia and we'll help you investigate. Have the following ready: what you were trying to do, what error message appeared (take a screenshot if possible), and which device and browser you were using.

Need a hand?

If you're stuck, email support@chykalophia.com and we'll help. Include your website address and a screenshot if you can.