How to fix outlook

Question

Outlook is constantly crashing or frozen, it is impossible to read or write

Answer 1

Hi! Let me help you with this issue.

Please follow the steps below on how to get this fixed.

Try opening Outlook in Safe mode.

Press Windows + R, type:

outlook.exe /safe

Press Enter.

If Outlook works normally in Safe Mode, the problem is likely a faulty add-in.

To disable add-ins:

Open Outlook

Click File > Options > Add-ins

At the bottom, select COM Add-ins and click Go

Uncheck all add-ins

Restart Outlook normally

If it works, re-enable add-ins one by one to find the problematic one.

If you are still having the same issue, run a quick repair.

Press Windows + R

Type:

appwiz.cpl

Press Enter

Select Microsoft 365 / Microsoft Office

Click Change

Choose Quick Repair

Restart your PC

If the issue continues, repeat the steps but choose Online Repair instead (this fully reinstalls Office).

Answer 2

Try the following steps in order until Outlook stops crashing or freezing.

1. Install the latest Windows and Office/Outlook updates

• Make sure Windows Update is set to install important and recommended updates.
• Install all pending Windows updates for the version in use.
• Install the latest Outlook/Office updates as described in [How to install the latest applicable updates for Microsoft Outlook (US English only)].

2. Check that Outlook isn’t busy with background tasks

• If AutoArchive is running or a mobile device is synchronizing, Outlook performance can drop and appear frozen.
• Wait for these operations to complete, then test again.

3. Reduce mailbox and folder size

• Very large mailboxes or folders can cause freezing when opening, moving, or deleting items.
• Create additional folders and move items out of large folders:
  1. On the Folder tab, select New Folder.
  2. Enter a name and choose where to place the folder, then select OK.
• Use AutoArchive or manual archiving to reduce .ost/.pst size as described in [Reduce the size of Outlook Data Files (.pst and .ost)] and [AutoArchive settings explained].

4. Check AppData redirection (if Outlook is slow/freezing on a domain or roaming profile)

• Outlook stores signatures and dictionaries in the AppData folder; if this is redirected to a slow network location, Outlook can hang.
• To disable AppData redirection:
  1. Exit Outlook.
  2. Press Windows key+R, type regedit.exe, select OK.
  3. Go to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders.
  4. Double‑click AppData and set Value data to %USERPROFILE%\AppData\Roaming, then select OK.
  5. Close Registry Editor and test Outlook.

5. Repair Office/Outlook installation

• Close all Office apps.
• Open Control Panel → Programs and Features.
• Right‑click the Microsoft Office installation and choose Repair (or Change → Repair depending on version).
• After repair completes, restart the computer and test Outlook.

6. Repair Outlook data files (.pst/.ost)

• Corrupted data files can cause crashes and hangs.
• Close Outlook.
• Run the Inbox Repair Tool (SCANPST.EXE) following the steps in [Repair Outlook Data Files (.pst and .ost)].
• Repeat the scan until no errors are reported, then reopen Outlook.

7. Check antivirus integration with Outlook

• Out‑of‑date or tightly integrated antivirus can cause Outlook to freeze.
• Update antivirus definitions from the vendor’s site (see [Consumer antivirus software providers for Windows]).
• If the product has Outlook integration or Outlook add‑ins, temporarily disable that integration or add‑ins and test again.
  • Note: Changing antivirus settings can increase exposure to threats; only do this if comfortable with the risk and consider re‑enabling protection after testing.

8. Create a new Outlook profile

• A corrupted Outlook profile can cause constant crashes.
• In Control Panel → Programs → User Accounts → Mail:
  1. Select Show Profiles.
  2. Select the existing profile and choose Remove (only if data is safely on the server or backed up).
  3. Select Add, enter a profile name.
  4. Enter user name, primary SMTP address, and password, then select Next.
  5. If prompted with “Allow this website to configure … server settings?”, check Don’t ask me about this again, then select Allow.
• Start Outlook with the new profile and test.

9. Perform a Selective Startup (clean boot) to find conflicting software

• Other programs or services can conflict with Outlook.
• In Control Panel → System and Security → Administrative Tools → System Configuration:
  1. On General, select Selective startup and clear Load system services and Load startup items.
  2. Re‑enable Load system services, select OK, then Restart.
  3. If the problem returns, use the Services tab to disable all, then re‑enable services one by one (restarting each time) until the problem reappears.
  4. Do the same on the Startup tab for startup items.
• For detailed clean‑boot guidance, see [How to perform a clean boot in Windows].

10. Use the Classic Outlook Advanced Diagnostics troubleshooter

• Run the Classic Outlook Advanced Diagnostics tool from the Get Help app as described in the article.
• It will run automated checks and propose targeted fixes for hanging/freezing and crash issues.

If Outlook still constantly crashes after all steps above, collect the results from the Classic Outlook Advanced Diagnostics troubleshooter and proceed with additional support options referenced in the documentation.

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References:

• Outlook not responding error or Outlook freezes when you open a file or send mail
• Outlook not responding, stuck at "Processing," stopped working, or freezes
• How to troubleshoot issues that cause Outlook to crash or stop responding when used with Microsoft 365
• Outlook Freezing and Not Responding and Not saving changes when ending the task - Microsoft Q&A
• Outlook not properly closed? - Microsoft Q&A
• What to do when Outlook will not open on my PC? - Microsoft Q&A
• Outlook keeps crashing - Microsoft Q&A
• New Outlook has stopped working, Fails when starting after 30 to 60 seconds - Microsoft Q&A