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Before changing anything, identify which Outlook you are trying to open. Windows 11 can have both versions installed:

  • New Outlook for Windows is the newer Microsoft Store app.
  • Outlook (classic) is the desktop application included with Microsoft 365, Office, Outlook 2021, Outlook 2024, and some older installations.

Open Start and search for Outlook. If the result is labelled Outlook (classic), follow the classic Outlook steps below. If you see new Outlook for Windows, use Step 1. The safe-mode, profile, COM add-in, and PST repair instructions in the remaining steps are for classic Outlook and do not apply to new Outlook.

If classic Outlook keeps redirecting you to new Outlook, launch it directly from Start > Outlook (classic). In new Outlook, the top-right menu also includes Switch back to classic Outlook and Use classic Outlook this time. The second option only opens classic Outlook once.

1. Close a stuck Outlook process

For new Outlook

New Outlook may still be running even when its window has disappeared. End the process before trying to open it again:

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  1. Right-click Start and select Task Manager.
  2. Select Microsoft Outlook in the list of processes.
  3. Select End task.
  4. Close Task Manager and start Outlook again.

Do not confuse End task with uninstalling Outlook. It only closes the currently stuck process.

If new Outlook still will not open, reinstall it from the Microsoft Store. To remove it, open Start > new Outlook for Windows, expand the entry with the arrow, and select Uninstall. Then open Microsoft Store, search for new Outlook, and select Get. If the Store shows Open, it is still installed rather than removed. Windows 11 meets Microsoft’s minimum requirement of Windows 10 version 17763.0 or later.

For classic Outlook

In Task Manager, look for Microsoft Outlook or an Outlook process, select it, and choose End task. Then try opening Outlook (classic) from Start. If it fails again, continue with the next step.

2. Start classic Outlook in Safe Mode

Safe Mode starts classic Outlook without the Reading Pane, toolbar customizations, or native and managed COM add-ins. This makes it a useful test when an add-in is preventing startup.

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  1. Press Windows key + R to open the Run dialog.
  2. Enter outlook.exe /safe.
  3. Select OK.
  4. If the Choose Profile window appears, accept the usual profile and select OK.
  5. Enter your account password if prompted, then select Accept.

You can also use Outlook /safe. The space between Outlook and /safe matters.

If Outlook opens in Safe Mode but not normally, an add-in is the likely cause. This test does not prove that your Outlook profile or data file is undamaged, so do not treat Safe Mode as a complete repair.

If Safe Mode also fails, skip to Step 4 and Step 5. Those steps test navigation settings and the Outlook profile rather than add-ins.

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3. Disable COM add-ins without removing them

If classic Outlook opened in Safe Mode, disable its COM add-ins and then restart normally:

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  1. In Outlook, select File > Options > Add-ins.
  2. At the bottom of the window, set Manage to COM Add-ins.
  3. Select Go.
  4. Clear the check box beside every enabled add-in.
  5. Select OK and restart Outlook normally.

Use the check boxes to disable add-ins. Do not select an add-in and choose Remove. If you have administrator rights, Remove can delete the add-in rather than merely turning it off.

To find the problem add-in, enable one item, restart Outlook, and test it. Repeat with the next item. When the startup failure returns, the most recently enabled add-in is implicated. More than one add-in can cause problems. An outdated ABBYY FineReader add-in is one known example Microsoft specifically identifies as a possible cause.

4. Reset the classic Outlook navigation pane

Use this step when Outlook reports Cannot start Microsoft Outlook or Cannot open the Outlook window, particularly after the Folder Pane or its shortcuts were customized.

  1. Close Outlook completely.
  2. Press Windows key + R.
  3. Enter Outlook.exe /resetnavpane.
  4. Select OK.

The command clears and regenerates the Folder Pane for the current Outlook profile. That is the left side of Outlook containing folders and navigation icons such as Mail, Calendar, People, and Tasks.

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This is a narrowly targeted reset. It does not repair Outlook, rebuild a profile, or fix PST or OST corruption. It removes local navigation-pane customizations, so Microsoft recommends running it separately on each computer where the problem occurs.

5. Create and test a new classic Outlook profile

A damaged profile can stop classic Outlook before its main window appears. Testing a new profile is a safer diagnosis than immediately deleting the old one.

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Open the profile picker

Hold Shift while starting Outlook. If that does not open the picker, press Windows key + R, enter Outlook.exe /profiles, and press Enter.

Create the test profile

  1. In the profile picker, select Options.
  2. Select New.
  3. Enter a name for the profile, such as Outlook Test.
  4. Select OK.
  5. Add the email account when prompted.
  6. Select the new profile and choose OK.

Try opening Outlook with the new profile. If it works, the original profile is probably corrupted or otherwise responsible for the startup failure. You can make Outlook ask which profile to use by selecting Prompt for a profile to be used in the profile picker.

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Do not remove the old profile until you have checked its data files and backed up anything important. Removing a profile deletes the offline cached content associated with it. An open Outlook session also provides File > Account Settings > Change Profile; Outlook restarts when you use that option.

6. Repair Office or the Outlook data file

Repair the Office installation

On Windows 11, the current Microsoft repair route is:

  1. Right-click Start.
  2. Select Installed apps.
  3. Find your Microsoft 365 or Office installation.
  4. Select the ellipsis (…) beside it.
  5. Select Modify.

This repairs the Office suite, even if Outlook is the only program that appears broken.

For a Click-to-Run installation, start with Quick Repair. It is faster and detects and replaces corrupted files. If that does not solve the problem, choose Online Repair > Repair. Online Repair is the more complete option and may require a stronger internet connection or sign-in again.

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For an MSI-based installation, select Repair under Change your installation, then select Continue.

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Repair a damaged PST file with SCANPST.EXE

If classic Outlook says it cannot open a data file or folder set, a damaged PST may be the cause. Microsoft’s Inbox Repair Tool is called SCANPST.EXE.

  1. Exit Outlook.
  2. Find and open SCANPST.EXE.
  3. Select Browse and choose the affected .pst file.
  4. Select Start.
  5. If errors are found, select Repair.

Back up the PST before repairing it. SCANPST creates a backup during repair, may need to be run more than once, and may not recover permanently deleted items or severely corrupted data.

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If you can open Outlook, locate the file through File > Account Settings > Account Settings > Data Files. This tab lists the PST and OST files and their associated accounts.

The path C:Program Files (x86)Microsoft OfficerootOffice16 is a published SCANPST location for Outlook 2019 and Outlook 2016, but it is not a universal path for every Microsoft 365, Office 2021, Office 2024, 32-bit, or 64-bit installation. Search for SCANPST.EXE if it is not there.

What about an OST file?

For an Exchange account, Microsoft says the offline .ost file can be deleted after Outlook is closed. Outlook recreates it the next time it opens. This advice does not apply to PST files. SCANPST also does not repair data stored in the Exchange mailbox itself.

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Which fix should you try first?

What you observe Best next step
New Outlook is frozen or its window vanished End the Microsoft Outlook task in Task Manager.
Classic Outlook opens only with /safe Disable COM add-ins one at a time.
“Cannot open the Outlook window” appears Run Outlook.exe /resetnavpane.
A new profile works normally Keep using the new profile after backing up old profile data.
Outlook reports a data-file or folder-set error Back up the PST and run SCANPST.EXE.
None of the startup tests work Run Office repair, beginning with Quick Repair and then Online Repair.

These instructions cover current classic Outlook versions including Outlook for Microsoft 365, Outlook 2024, and Outlook 2021. Microsoft’s broader startup guidance also covers Outlook 2019 and Outlook 2016, although support for older Office 2016 and Office 2019 clients connecting to Microsoft 365 services has ended.

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FAQ

Why does Outlook open in Safe Mode but not normally?

A COM add-in is the most likely cause. Open File > Options > Add-ins, select COM Add-ins under Manage, choose Go, and clear the enabled add-ins. Re-enable them one at a time to identify the one that causes the failure.

Does /resetnavpane repair Outlook’s PST or OST file?

No. Outlook.exe /resetnavpane only clears and regenerates Folder Pane customizations for the current profile. Use SCANPST.EXE for a damaged PST, or create a new profile when the profile itself is suspected.

Can these steps fix new Outlook for Windows?

Only Step 1 applies directly to new Outlook. New Outlook does not use the classic Outlook COM-add-in, profile, and PST troubleshooting sequence. End its task in Task Manager or reinstall it from the Microsoft Store.

Will creating a new Outlook profile delete my email?

Creating a profile does not delete the original profile. However, removing an old profile deletes its offline cached content, so back up relevant data files before removing it. Server-based mailbox data remains on the server.

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Where is SCANPST.EXE in Windows 11?

Its location depends on the Outlook edition, installation type, and architecture. The path C:Program Files (x86)Microsoft OfficerootOffice16 is documented for some Outlook 2016 and 2019 installations, but it is not universal. Search the Office folders or Windows for SCANPST.EXE.

The Bottom Line

Start by separating new Outlook from classic Outlook. For new Outlook, end the stuck Microsoft Outlook task or reinstall the Store app. For classic Outlook, test Safe Mode, disable COM add-ins, reset the navigation pane, test a new profile, and then repair Office or the relevant PST file. Avoid deleting add-ins, profiles, or data files until you have backed up anything you may need.

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