Fixes / Outlook · Checked

Something went wrong and Outlook couldn't start: how to fix it

Short answer

This message means Outlook crashed while loading, usually because its local cache or saved sign-in data is corrupted. In new Outlook for Windows, the most reliable fix is to close Outlook, open %LocalAppData%\Microsoft, delete the Olk folder, and open Outlook again. In classic Outlook, start it with outlook.exe /safe to check whether a faulty add-in is the cause.

What this message means

Outlook began to start but hit an error before it could show your mailbox, so it stopped and showed this message instead of crashing silently. Your email is not lost. For Microsoft 365, Outlook.com and Exchange accounts the mail is stored on the server, and you can read it at outlook.office.com or outlook.com while you fix the app. The problem is almost always on your PC: a corrupted local cache or settings folder, stale sign-in tokens, a broken add-in (classic Outlook), damaged Office program files, or a damaged Outlook profile or data file. It often appears right after an Outlook or Windows update.

Common causes

CauseHow to tell
Corrupted local data in new Outlook for Windows (the Olk folder)You use new Outlook (the app has a 'New Outlook' toggle, or it is listed as 'Outlook (new)' or 'Outlook for Windows' under Installed apps). The error appears every time you open it, often right after an update, while Outlook on the web works normally.
Stale or broken sign-in data for a work or school accountThe error sometimes includes a short code in brackets such as [7q6ch], or Outlook briefly shows a sign-in window before failing. Teams or other Microsoft 365 apps may also ask you to sign in again or fail to sign in.
A faulty COM add-in in classic OutlookOutlook opens fine when you run outlook.exe /safe (the title bar shows 'Safe Mode') but fails when opened normally. The problem often starts after installing or updating a program that adds a toolbar to Outlook, such as a PDF tool, antivirus, CRM or meeting plugin.
Damaged Office program filesOutlook fails even in safe mode, and Word or Excel may also crash or show their own 'Something went wrong' message. It often follows an interrupted update or an unexpected shutdown.
Damaged classic Outlook profile or data file (.pst/.ost)Outlook fails in both normal and safe mode, Office apps other than Outlook work, and Outlook opens correctly once you create and select a new profile.

How to fix it

1. Fully close Outlook and restart the PC

  1. Right-click the Start button and choose Task Manager.
  2. On the Processes tab, select any 'Microsoft Outlook' or 'Outlook (new)' entry and click End task.
  3. Restart the computer (use Restart, not Shut down, so Windows fully reloads).
  4. Open Outlook again. If the error comes back, check your mail at outlook.office.com (work or school) or outlook.com (personal) to confirm your account works, then continue below.

2. Delete the Olk cache folder (new Outlook)

New Outlook for Windows (Windows 10 and 11)

  1. Close Outlook and make sure it is ended in Task Manager.
  2. Press Windows key + R, type %LocalAppData%\Microsoft and press Enter.
  3. Delete the folder named Olk. This clears only local cached data. Mail stored on the server is not affected.
  4. If you use a work or school account, also delete the OneAuth and IdentityCache folders in the same location if they exist.
  5. Restart the PC, open Outlook and sign in again when asked. As an alternative to deleting folders, some users run olk.exe --clearLocalState from Windows key + R.

3. Repair or reset the new Outlook app

New Outlook for Windows. In Windows 11 the path is Settings > Apps > Installed apps. In Windows 10 it is Settings > Apps > Apps & features.

  1. Press Windows key + I to open Settings, then go to Apps > Installed apps.
  2. Find Outlook for Windows (it may be listed as Outlook (new)), click the three dots (in Windows 10, select the app) and choose Advanced options.
  3. Under Reset, click Repair, then try opening Outlook.
  4. If it still fails, click Reset. This removes the app's local data, so you may need to sign in again and redo settings such as your signature.
  5. If Reset does not help, uninstall Outlook for Windows, delete the Olk folder as described above, and reinstall it from the Microsoft Store.

4. Start classic Outlook in safe mode and turn off add-ins

Classic Outlook for Windows (Microsoft 365, Outlook 2016, 2019, 2021, 2024)

  1. Press Windows key + R, type outlook.exe /safe and click OK. Pick your profile and click OK if asked.
  2. If Outlook opens (the title bar shows 'Safe Mode'), go to File > Options > Add-ins.
  3. Next to Manage, choose COM Add-ins and click Go.
  4. Write down which add-ins are checked, uncheck all of them and click OK.
  5. Close Outlook with File > Exit, then open it normally. If it works, turn the add-ins back on one at a time to find the one causing the error.

5. Repair Microsoft Office

Classic Outlook installed as part of Microsoft 365 or Office. Windows 11: right-click Start > Installed apps, then the three dots > Modify. Windows 10: right-click Start > Apps and Features > Modify.

  1. Close all Office apps.
  2. Right-click the Start button and choose Installed apps (Windows 11) or Apps and Features (Windows 10).
  3. Find your Microsoft 365 or Office entry and choose Modify.
  4. Select Quick Repair and click Repair. Test Outlook when it finishes.
  5. If the error continues, repeat and choose Online Repair. It takes longer and needs an internet connection, but it replaces every Office file.

6. Create a new Outlook profile or run the startup troubleshooter

Classic Outlook for Windows

  1. Open Control Panel (search for it from Start), set View by to Large icons and open Mail (Microsoft Outlook).
  2. Click Show Profiles, then Add, name the profile and follow the prompts to add your email account.
  3. Select 'Prompt for a profile to be used', click OK, then open Outlook and choose the new profile.
  4. If Outlook now opens, set the new profile as the default in the same Mail window. Old .pst files can be reopened from File > Open & Export.
  5. If you prefer an automated check, run Microsoft's classic Outlook startup troubleshooter from aka.ms/SaRA-OutlookWontStart (Windows 10 or later).

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Still not fixed?

Use Outlook on the web (outlook.office.com for work or school accounts, outlook.com for personal accounts) in the meantime. Your mail, calendar and contacts are all there. If you use new Outlook, you can switch back to classic Outlook with the toggle in the app or from the Start menu if it is installed, which often works while the new app is broken. For a work or school account, contact your IT department, since sign-in policies, conditional access or a managed add-in may be blocking Outlook. Home users can uninstall and reinstall Microsoft 365 from account.microsoft.com, or contact Microsoft Support through the Get Help app in Windows.

Questions people ask

Will I lose my emails if I delete the Olk folder or reset Outlook?

No, not for Microsoft 365, Outlook.com, Gmail or other server-based accounts. The Olk folder only holds a local copy that Outlook downloads again. You may need to sign in again and redo local settings such as your signature.

Why did Outlook stop starting after an update?

Updates can leave the local cache or settings in a state the new version cannot read, which makes Outlook fail during startup. Clearing the cache (new Outlook) or running a Quick Repair (classic Outlook) usually fixes it.

What does the code [7q6ch] mean?

It usually points to a sign-in failure with a work or school account in new Outlook. Deleting the Olk, OneAuth and IdentityCache folders in %LocalAppData%\Microsoft and signing in again typically fixes it. If not, ask your IT admin to check your account.

Can I still read my email while Outlook won't start?

Yes. Sign in at outlook.office.com (work or school) or outlook.com (personal), or use the Outlook mobile app. Both work independently of the desktop app.

How do I know if I have new Outlook or classic Outlook?

New Outlook shows a 'New Outlook' toggle at the top and appears as 'Outlook (new)' or 'Outlook for Windows' in Installed apps. Classic Outlook has a File tab with Options and Account Settings.

Sources

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