My Outlook does not work

Hi Preben Arnfjord,

Welcome to Microsoft Q&A forum. 

To narrow down the root cause (Windows/Office updates, PST/POP, add-ins, antivirus, or a corrupted profile/data file), please share these details:

• Which Outlook are you using: Classic Outlook / New Outlook / Outlook on the web / Mac / Mobile?
• What type of account is affected: Microsoft 365/Exchange / Outlook.com (Hotmail) / IMAP / POP?
• Are you on Windows 10 or Windows 11? Did the issue start right after a Windows Update or Office update (if yes, please share the KB number / most recent update name)?
• If you use POP + a .PST file: is the PST stored in OneDrive or a cloud‑synced folder?
• At what point does Outlook freeze: when launching / syncing the inbox / opening an email / sending an email?

Note: If you are using Classic Outlook + POP + PST and the problem started after a Windows Update, try updating Windows to a newer build and make sure the PST is not stored in OneDrive/a cloud‑synced folder.

Once you share the above, the most suitable fix steps can be provided based on your exact setup.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

The freezing and crashing can usually be narrowed down and fixed by working through a few targeted steps. Follow these in order and test Outlook after each major step.

1. Check whether Outlook is actually “busy”

• Look at the status bar at the bottom of the Outlook window. If it shows operations like sending/receiving a large attachment, auto-archiving, or processing many items, let it run for a few minutes. Outlook can appear frozen while it completes these background tasks.

2. Start Outlook in Safe Mode This helps rule out add-ins and some customizations.

• Close Outlook.
• In Windows, open Start and run:
  • Outlook.exe /safe (or Outlook /safe depending on version).
• If Outlook runs normally in Safe Mode, disable or remove any non‑Microsoft add-ins.

3. Make sure Windows and Office are fully updated

• Install the latest Windows and Office updates. Bug fixes and performance improvements are released regularly and can resolve freezing and crash issues.
• For Office, see: Install Office updates.

4. Repair Office Corrupted Office binaries commonly cause repeated crashes.

• Close all Office apps.
• Open Control Panel → Programs and Features (or “Uninstall a program”).
• Find the Microsoft 365/Office installation, right‑click it, and choose:
  • Change → Repair (or Online Repair if available and basic repair doesn’t help).

5. Repair Outlook data files (.pst / .ost) If data files are damaged, Outlook can hang, lose changes, or crash.

• Close Outlook.
• Run the Inbox Repair Tool (SCANSPST.EXE) and follow the steps in Repair Outlook Data Files (.pst and .ost).
• After repair, reopen Outlook and test.

6. Check for known POP account / Windows update issues If using POP accounts and Windows 11:

• There is a known bug where POP profiles hang and freeze after a specific Windows update (KB5074109). The documented temporary fix is to uninstall that January 2026 update from Settings → Windows Update → Update history → Uninstall updates, then remove that KB if present.

7. Create a new Outlook profile Profiles can become corrupted and cause loops, freezes, or crashes.

• Close Outlook.
• Open Control Panel → User Accounts → Mail → Show Profiles.
• Select the existing profile and choose Remove (only if data is backed up or stored on the server; otherwise skip removal and just add a new one).
• Select Add, give the profile a name, and re‑add the email account(s).
• Set the new profile as default and test.

8. Check antivirus integration

• Out‑of‑date or tightly integrated antivirus can conflict with Outlook and cause performance issues.
• Update the antivirus to the latest version.
• If it has Outlook integration or add‑ins, temporarily disable that integration or those add‑ins to test. Be aware this can reduce protection; change these settings at own risk.

9. Advanced: Windows user profile If Outlook still freezes after all of the above, the Windows user profile itself may be corrupted.

• Create a new Windows user account/profile.
• Sign in with that new account, configure Outlook, and test whether the freezing persists.

If the problem started immediately after a specific Windows update and affects multiple machines, focus on step 6 (uninstalling the problematic KB) and then re‑test Outlook.

References:

• Outlook not responding, stuck at "Processing," stopped working, or freezes
• Troubleshoot Outlook for Windows issues
• Outlook not responding error or Outlook freezes when you open a file or send mail
• Outlook crashes or stops responding when used with Office 365
• Outlook Freezing and Not Responding and Not saving changes when ending the task - Microsoft Q&A
• Outlook keeps crashing - Microsoft Q&A