Microsoft Outlook keeps crashing

If Microsoft Outlook keeps crashing, the problem is usually a damaged add-in, a broken Outlook profile, or a corrupted local data file. This guide walks you through the fastest fixes first so you can get Outlook open again and keep it from closing the moment you launch it.

Quick fix

The single most likely fix is to start Outlook in Safe Mode and disable add-ins. Bad add-ins are a common reason Outlook opens, freezes, and then crashes again on the next launch. If Safe Mode works, you can turn the add-ins back on one by one to find the one causing the crash.

Why this happens

Outlook crashes when one of its startup pieces fails: an add-in hooks into the app and breaks it, a profile becomes corrupted, or Outlook trips over a damaged local cache or data file. A recent sync problem, a faulty update, or a mailbox with too much old cached data can push it over the edge. The crash repeats because Outlook loads the same broken component every time it starts.

How to fix it

1. Start Outlook in Safe Mode.
   Press Windows + R, type outlook /safe, and press Enter. If Outlook opens normally in Safe Mode, the core app is fine and the crash is coming from an add-in or custom setting. Leave Outlook open for a minute and click around the inbox to confirm it stays stable.

2. Turn off COM add-ins.
   In Outlook, go to File > Options > Add-ins. At the bottom, next to Manage: COM Add-ins, click Go, clear every check box, and then click OK. Close Outlook and open it again normally. If it stops crashing, turn the add-ins back on one at a time until the crash returns; the last one you enabled is the problem. If you also use other Office apps, a broken add-in can affect more than Outlook, so see fix Office app add-ins for a deeper cleanup.

3. Create a new Outlook profile.
   Close Outlook, then open Control Panel > Mail > Show Profiles. Click Add, give the new profile a name, and add your email account again. Set the new profile as Always use this profile, then launch Outlook. A fresh profile rebuilds the account settings and often fixes crashes caused by damaged profile data.

4. Repair your Outlook data file.
   Close Outlook completely. Open File Explorer and run SCANPST.EXE from your Microsoft Office folder, then choose your Outlook data file and start the repair. When the scan finishes, reopen Outlook and test again. If Outlook uses cached Exchange mode, a damaged local cache can trigger repeated crashes; rebuilding the cache is the next step if the repair does not hold.

5. Rebuild the local cache.
   Close Outlook, then go to Control Panel > Mail > Email Accounts > Data Files and note the location of the .ost file if your account uses one. Rename that file by adding .old at the end, then reopen Outlook so it creates a fresh cache from the server. This is a clean way to fix crashes caused by corrupted synced mail, calendar, or contact data without changing the account itself.

6. Repair Microsoft Outlook from Windows settings.
   Open Settings > Apps > Installed apps. Find Microsoft 365 or Microsoft Office, click the three dots, choose Modify, and run Quick Repair first. If Outlook still crashes, run Online Repair next. Quick Repair fixes damaged program files locally; Online Repair replaces the full Office installation and clears stubborn corruption that survives a normal reinstall.

Common error messages

“Microsoft Outlook has stopped working”
This means Outlook crashed during startup or while loading a component, which is most commonly caused by a bad add-in or a damaged profile.

“Outlook cannot start because a dialog box is open”
This usually appears when Outlook is stuck behind a hidden prompt, stuck add-in dialog, or a broken startup window that prevents the app from finishing launch.

“Something went wrong and Outlook quit unexpectedly”
This points to a deeper app or data problem, such as a corrupted cache, a broken Office file, or a failing profile that crashes as soon as Outlook connects to your mailbox.

When this means it’s a bigger problem

If Outlook still crashes after Safe Mode, a brand-new profile, and an Online Repair on a fresh Office install, the problem is no longer a simple local corruption issue. That pattern points to a damaged mailbox, a sync conflict on the server, or a broader Office installation problem tied to your account or device. At that point, stop troubleshooting the desktop app and contact official Microsoft support or your workplace IT team with the exact crash behavior and any error text you saw.

Frequently Asked Questions

Q: How long does it take for Outlook to stop crashing after I disable add-ins or repair it?
If add-ins are the cause, Outlook stops crashing the next time you launch it normally. A new profile or data-file repair works as soon as you reopen Outlook and let it finish loading. Quick Repair finishes faster than Online Repair, which takes longer because it replaces Office files.

Q: Will creating a new Outlook profile delete my emails or contacts?
No. A new Outlook profile changes the local account configuration, not the mailbox itself. Your mail, calendar, and contacts stay on the server and come back when you add the account again. The only thing you lose is profile-specific local settings, such as custom views, signatures, and account order.

Q: What if Outlook still crashes after Safe Mode, a new profile, and Online Repair?
That points to a mailbox-side or account-side problem instead of a simple app issue. At that stage, check for server sync conflicts, a damaged mailbox, or a policy issue on your work account. If you need a deeper route for stubborn startup failures, work through Outlook startup errors next.

Q: Can I undo the OST cache rebuild if Outlook starts acting worse afterward?
Yes. Renaming the .ost file does not erase your server mailbox, and Outlook can create a fresh cache again at any time. If the new cache behaves badly, close Outlook, delete the new .ost, and let Outlook rebuild it once more. Your synced mail returns from the server.

Q: Is Quick Repair enough, or should you go straight to Online Repair?
Run Quick Repair first because it fixes the common local file damage without replacing the full Office installation. Use Online Repair when Quick Repair does not stop the crashes. Online Repair is the stronger fix because it replaces corrupted Microsoft Office components that a basic repair leaves behind.