How to Open Outlook in Safe Mode (and Find the Add-in Causing Trouble)

The point of safe mode is diagnosis, not a fix. Microsoft says that starting Outlook without add-ins can tell you if an add-in is the source of the problem. If Outlook opens fine in safe mode, an add-in is the likely culprit. If it won't open even in safe mode, the problem's somewhere else, and Microsoft's next suggestions are your profile and your data files. Either answer tells you where to look next.

Three ways to start Outlook in safe mode

Method	What you do, as of October 2026
Run box	Press the Windows key + R, or right-click Start and click Run, then type outlook.exe /safe and click OK
Ctrl key	Find the Outlook shortcut, hold CTRL and double-click it, then click Yes
Start search in Windows 10	Choose Start, type Outlook.exe /safe and press Enter
Windows 8	On the Apps menu, choose Run, type Outlook /safe and choose OK
Windows 7	Choose Start, type Outlook /safe in the Search programs and files box and press Enter

Step by step with the Run box

1. Close Outlook if it's open or frozen.
2. Press the Windows key + R to open the Run dialog. It usually appears near the lower left of your screen.
3. In the Open box, type Outlook.exe /safe, then choose OK.
4. If a Choose Profiles dialog box appears, accept the default setting of Outlook and choose OK.
5. If prompted, enter your password and choose Accept.

If Windows can't find Outlook.exe /safe, Microsoft's tip is to use the full path to Outlook instead, for example C:\Program Files\Microsoft Office\OfficeXX, where XX is your version number.

How you'll know safe mode's on

Microsoft says you'll see a safe mode label at the top of the screen, and the Outlook icon on your taskbar includes an exclamation symbol to warn you the program isn't running normally. To stop Office Safe Mode, exit and restart Outlook. Microsoft says it'll start in normal mode unless there's a problem opening it.

Don't mix this up with Windows safe mode. Microsoft is explicit that Office Safe Mode is different: it only changes how the Office app starts, not your whole PC.

The fix for Outlook stuck on Processing

There's one case where safe mode is the fix as well as the test. If classic Outlook stops responding at a screen that says Processing, Microsoft's advice is to close Outlook, start it in safe mode, then close it and open it normally. If it wasn't stuck on Processing, or that didn't help, carry on with the add-in steps below.

Before you blame an add-in, Microsoft suggests two quick checks. Look for an open dialog box, because Outlook won't let you do anything else until you answer one: pressing Alt+Tab switches between windows so you can find it. Then check the status bar at the bottom of the screen. If Outlook is deleting or moving hundreds or thousands of messages, or running something like Auto-archive, it can look frozen while it's working. Give it a few minutes.

What safe mode switches off

Safe mode is meant for getting in and finding the problem, not for working in all day. Microsoft lists the restrictions, and notes that not all of them apply to every Office program:

• No templates can be saved.
• Toolbar or command bar customisations aren't loaded, and new ones can't be saved.
• The AutoCorrect list isn't loaded, and changes aren't saved.
• Recovered documents aren't opened automatically.
• All command-line options are ignored except /a and /n.
• Preferences can't be saved.
• Additional features and programs aren't loaded automatically.
• Documents with restricted permission can't be created or opened.

Finding the add-in that's breaking Outlook

If Outlook opens in safe mode, Microsoft's process is to switch every COM add-in off, then bring them back one at a time until the problem returns.

1. In Outlook, choose File > Options > Add-ins.
2. At the bottom, make sure the Manage box shows COM Add-ins, then choose Go.
3. Write down the title of every selected add-in, or take a screenshot, so you know what to switch back on.
4. Clear all the selected check boxes, then choose OK.
5. Choose File > Exit, then restart Outlook normally.
6. Go back to COM Add-ins, tick one add-in, choose OK, and restart Outlook. Repeat until the problem comes back.

The add-in you enabled just before the problem returned is your culprit. Restart Outlook in safe mode again and switch that one off. Microsoft adds that more than one add-in can cause an error, so go through the restart, disable, restart process for every add-in that was originally on.

One warning from Microsoft is worth repeating: click a check box to clear it, and don't select an add-in and choose Remove. If you have administrator rights, Remove can delete the add-in rather than disable it. Microsoft also flags that an outdated ABBYY FineReader add-in might cause an Outlook startup error.

Automated safe mode and the Disabled Items list

Sometimes Office goes into safe mode by itself. Microsoft calls this automated safe mode, and it's triggered when an Office app can't start because of something like an add-in or extension that won't load, or a corrupted file, registry entry or template. You'll get a message naming the problem and asking whether to disable that part of the app.

To see what's been switched off, go to File > Options > Add-Ins, choose Disabled Items on the Manage menu and click Go. You can select an item and click Enable to turn it back on, but if it causes the same problem next time, you'll be asked to disable it again.

If Outlook won't open even in safe mode

Then add-ins aren't the cause, and Microsoft's next steps are these:

• Create a new Outlook profile. Your profile holds your Outlook settings and can become corrupted. In Windows 10, open Control Panel, then User Accounts > Mail > Show Profiles, choose Add and set up your main account. Choose Prompt for a profile to be used, or hold Shift while restarting Outlook, and pick the new profile. Back up your data files before you remove an old profile, because offline cached content is deleted.
• Repair your data files. Exit Outlook and run the Inbox Repair Tool, scanpst.exe, which scans your Outlook data files and repairs errors.
• Reset the navigation pane. Close Outlook, press the Windows key + R and type Outlook.exe /resetnavpane. It removes your folder pane customisations, so run it on each computer where you use Outlook.
• Repair Office. Try a quick repair first, then the online repair if that doesn't work.
• Run the startup troubleshooter. Microsoft's classic Outlook startup troubleshooter needs Windows 10 or higher, on the same PC as Outlook.

New Outlook doesn't work the same way

Everything above is for classic Outlook for Windows. If you're on new Outlook for Windows, Microsoft's steps are different. To restart it, right-click Start, select Task Manager, select Microsoft Outlook and then End task, and reopen it as normal. If that doesn't help, uninstall it from the Start menu and reinstall it from the Microsoft Store, which needs Windows 10 version 17763.0 or later.

My verdict on Outlook safe mode

I'd open Outlook in safe mode the moment it crashes on startup, hangs on Processing or starts behaving oddly after you've installed something, because it answers the add-in question quickly. I'd skip it if you're on new Outlook, where it doesn't apply. If safe mode works, turning add-ins off one at a time is tedious but it's the method Microsoft uses. If it doesn't, my guide to Outlook not working covers the wider fixes, and it's worth checking you update Outlook as well, since Microsoft says updates often correct these problems.

Frequently asked questions

How do I start Outlook in safe mode?

Press the Windows key + R, type outlook.exe /safe in the Run box and click OK. Or hold CTRL while you double-click the Outlook shortcut and click Yes.

How do I get Outlook out of safe mode?

Exit Outlook and start it again normally. Microsoft says it'll open in normal mode unless there's a problem opening it.

What does Outlook safe mode turn off?

Safe mode starts Outlook without add-ins. Microsoft also lists other restrictions: preferences can't be saved, customisations aren't loaded and templates can't be saved.

Why can't Windows find Outlook.exe /safe?

Microsoft suggests using the full path to Outlook instead, for example C:\Program Files\Microsoft Office\OfficeXX, where XX is your version number.

Does safe mode work in new Outlook for Windows?

Microsoft's safe mode steps are for classic Outlook. For new Outlook, it suggests ending the task in Task Manager and reopening, or reinstalling from the Microsoft Store.