01202 775566 Book SOS REMOTE SUPPORT

Outlook fix | Windows | classic & new Outlook

Outlook opens then closes immediately? Here's why, and the fix

When Outlook opens then closes immediately, or crashes as soon as you open it, the cause is often something running at start-up: a faulty add-in, a damaged data file, or a corrupt profile. Start Outlook in Safe Mode first, because if it stays open that tells you exactly where to look. Below is the plain-English, step-by-step fix for both classic and new Outlook on Windows, and if you would rather not touch it, we will fix it for you remotely, usually in minutes.

Call 01202 775566 Fix it with me
Rated 4.9 on GoogleFamily-run since 1995 · no fix, no fee

By the 365 Techies team · Reviewed 10 October 2026

Answer first

The quick answer: start Outlook in Safe Mode

If Outlook opens then closes immediately, the fastest way to find the culprit is to launch it in Safe Mode, which loads Outlook without any add-ins.

  1. Close Outlook completely.
  2. Press the Windows key + R to open the Run box.
  3. Type outlook.exe /safe (there is a space before the slash) and press OK.

If Outlook stays open in Safe Mode, an add-in is crashing it — jump to the add-in fix below. If it still closes even in Safe Mode, the problem is the data file or profile — go to the repair and profile steps. This one test tells you which half of the guide you need, so you don't waste time.

// WINDOWS PCS ONLY

We do not support Outlook on Apple Macs, iPads or iPhones. Apple does not allow our remote-support tool to take control of an iPad or iPhone (an Apple restriction), and our remote support covers Windows PCs only. On an Apple device, Microsoft’s own Outlook help is the place to start.

// FIX IT WITH ME · STEP BY STEP

Fix it with me, one step at a time

The steps from this guide, one at a time, in the order that fixes the most cases fastest. Tell it what happened and it shows the next step. Nothing here leaves your device.Last reviewed 10 October 2026

Checking which Windows you have…STEP 1 OF 6
  1. 01Start Outlook in Safe Mode

    Close Outlook, press Windows key + R, type outlook.exe /safe (space before the slash) and click OK. If Outlook stays open, an add-in is the cause; if it still closes, the data file or profile is the problem.

    Is it working now?

Rather have it done for you? Remote help from £20, or in person across Bournemouth, Christchurch, Poole, Ringwood and the New Forest, with no call-out fee.

Outlook keeps closing on you? Our free Techies One Mail is a separate, simpler email program for Windows PCs that can show the email kept with your provider, though it won’t repair Outlook or open its .pst files.

// NEED THIS FIXED RIGHT NOW?

Skip the DIY — call 01202 775566 and we can be looking at your screen within minutes. You watch everything we do, and most problems on this page are fixed in one short remote session. (Mon–Fri, 9am–5pm.)

Start SOS Remote Support Call 01202 775566

The real fixes

Step-by-step fixes for classic Outlook

1. Disable the faulty add-in (a common cause). With Outlook open in Safe Mode, go to File > Options > Add-ins. At the bottom, next to Manage, choose COM Add-ins and click Go. Untick every add-in, click OK, then close and reopen Outlook normally. If it now stays open, re-enable the add-ins one at a time (reopening Outlook after each) until it crashes again — that last one is the offender. Leave it disabled or check for an update.

2. Watch out for the Teams Meeting Add-in crash. Since 12 March 2026, older classic Outlook builds (Version 2402, Build 17328.20142 or lower) can crash on launch because of a clash between the newest Teams Meeting Add-in and an older Windows file (MSVCP140.dll) bundled with those Office builds. If that is you, the real fix is to update Office: because Outlook won't open, open Word instead and go to File > Account > Update Options > Update Now. As a temporary workaround you can untick the Microsoft Teams Meeting Add-in for Microsoft Office via the Safe Mode add-ins steps above. Microsoft has also shipped a Teams-side fix, so keeping both Office and Teams up to date resolves it.

3. Repair Office. If no add-in is to blame, run an Office repair. Close all Office apps, then go to Settings > Apps > Installed apps, find Microsoft 365 (or Office), click the three dots and choose Modify, then Quick Repair. If that doesn't help, run Online Repair (this needs an internet connection and takes longer). Your emails are not touched by this.

4. Repair the data file with scanpst.exe. A corrupt Outlook data file can crash it on open. Close Outlook and run the built-in Inbox Repair Tool, scanpst.exe, usually found in C:\Program Files\Microsoft Office\root\Office16. Browse to your .pst file, click Start, and let it repair — it keeps a .bak backup and fixes the file in place. (For a damaged .ost, Microsoft's advice is to delete it and let Outlook rebuild it from the server.)

5. Create a new Outlook profile. If the profile itself is damaged, a fresh one often cures the crash. Close Outlook, open Control Panel > Mail (Microsoft Outlook) > Show Profiles > Add, create a new profile, add your account, and set it as the default. For IMAP, Exchange and Microsoft 365 accounts your mail re-downloads from the server, so nothing is lost — but if you have any POP account, back up your .pst file first, because POP mail lives only on your PC.

6. Check your antivirus isn't quarantining Outlook. Occasionally security software wrongly flags Outlook and blocks it from staying open. Open your antivirus, check its quarantine and protection history, and add Outlook (outlook.exe) as an exception if it has been blocked.

New Outlook

Fix for the new Outlook app

The new Outlook doesn't use add-ins or profiles in the same way, so if new Outlook opens then closes immediately, reset its local cache and sign-in files:

  1. Close new Outlook (check no olk.exe is still running in Task Manager).
  2. Press Windows key + R, type %localappdata%\Microsoft and press Enter.
  3. Find the folders named Olk and OneAuth.
  4. Right-click each and choose Rename — add .bak to the end (so they become Olk.bak and OneAuth.bak).
  5. Start new Outlook again and sign back in when prompted (you may be asked to complete MFA again).

These two folders only hold temporary cache and cached sign-in tokens — not your actual emails, which live safely on Microsoft's servers — so renaming them is reversible and nothing is lost. If it works, you can delete the .bak folders later. If new Outlook still won't stay open, it is quicker to let us take a look than to keep fighting it.

// KEEP GOING

Outlook not sending emailsOutlook keeps asking for your passwordnew Outlook won't openOutlook data file cannot be accessedMicrosoft 365 supportremote IT supportIT support in Dorsetcontact us

FAMILY-RUN SINCE 1995 · ★ 4.9 ON GOOGLE · 200+ COMPUTERS UNDER OUR CARE · NO FIX, NO FEE · SAME-DAY REMOTE SUPPORT

// GOOD QUESTIONS

Frequently asked

Why does Outlook open then close immediately?

Often something loads at start-up and crashes Outlook: a faulty add-in (very common), a corrupt Outlook data file (.pst/.ost), or a damaged profile. Starting Outlook with outlook.exe /safe skips add-ins — if it then stays open, an add-in is your culprit; if it still closes, look at the data file and profile.

How do I open Outlook in Safe Mode?

Close Outlook, press Windows key + R, type outlook.exe /safe (with a space before the slash) and click OK. Safe Mode loads Outlook without any add-ins, so it's the quickest way to tell whether an add-in is causing the crash.

Outlook crashes as soon as I open it since March 2026 — is that a known bug?

Yes. Older classic Outlook builds (Version 2402 / Build 17328.20142 or lower) started crashing on launch from 12 March 2026, due to a clash between the newest Teams Meeting Add-in and an older Windows file (MSVCP140.dll). The fix is to update Office (open Word, then File > Account > Update Options > Update Now) or untick the Microsoft Teams Meeting Add-in via Safe Mode. Keeping Teams updated also resolves it.

Will I lose my emails if I create a new profile or run scanpst?

scanpst.exe backs up your data file first and repairs it in place, though mail that is corrupted beyond repair may not come back. For Microsoft 365, Exchange and IMAP accounts, a new profile re-downloads everything from the server, so nothing is lost. The only account type where mail lives solely on your PC is POP — back up your .pst file before touching the profile if you use POP.

The new Outlook app closes the moment it opens — what do I do?

Close new Outlook, press Windows key + R, type %localappdata%\Microsoft, and rename the Olk and OneAuth folders (add .bak to each). Restart new Outlook and sign in. These folders only hold cache and cached logins, not your emails, so it's safe and reversible.

Can 365 Techies fix this remotely?

Yes. We connect securely with Splashtop SOS while you watch, phone you first before starting, and access ends the moment it's fixed. Often an Outlook-won't-open crash is sorted in minutes, the same day. Call 01202 775566.

// Still stuck?

Outlook still closing the second it opens?

Call 365 Techies on 01202 775566. We watch, we phone you first, and access ends the moment it's fixed. Same-day, usually sorted in minutes.

We’ll fix it with you

  • Checking the problem is free
  • Fixes from £20, agreed before we start
  • We phone first, and you watch every step
Fix it for me remotelyHow remote help works

Stop it happening again

  • A full service every six weeks, written up
  • Every program kept up to date
  • Unlimited remote help when you need it

Plans from £18.25 a month per computer · cancel any time

See plans & pricesOr get our free app

Mon–Fri 9–5 · family-run since 1995 · rated 4.9 on GoogleSee remote IT support →