If you are wondering Why does Outlook keep crashing on startup?, you are not alone. Many Windows users experience sudden crashes, freezes, or repeated restarts when they try to launch Microsoft Outlook. This issue can arise due to faulty add-ins, damaged PST/OST files, incorrect profile settings, outdated Outlook builds, or conflicts with your system applications. In this detailed guide, you will learn why this problem occurs and how to fix it using both manual solutions and the automated SysTools PST Repair Tool that works for all Outlook versions, including Outlook 365, 2021, 2019, and 2016.

Understanding why Outlook crashes on startup even in safe mode is crucial, because if ignored, it may lead to data loss, corruption, or permanent inaccessibility of your Outlook mailbox. The methods below will help you diagnose the cause and fix the crashing issue effectively.

Common Reasons Why Outlook Crashes When Starting

Before learning how to fix the problem, let’s understand Why does Outlook keep crashing on startup? Here are the most common causes:

  • Corrupted PST or OST data files

  • Faulty or incompatible Outlook add-ins

  • Issues with the Outlook navigation pane

  • Outdated Office or Windows updates

  • Corrupt Outlook profile

  • Conflicts with antivirus tools

  • Low system resources or bad system settings

Once you identify the cause, fixing the issue becomes much easier. Below are the proven solutions you should follow in sequence.

Fix 1: Start Outlook in Safe Mode

The first and easiest way to troubleshoot Why does Outlook keep crashing on startup? is to open it in Safe Mode, which temporarily disables all add-ins and custom settings.

  1. Press Windows + R to open the Run dialog box.

  2. Type outlook.exe /safe and press Enter.

  3. Outlook will open in Safe Mode without any add-ins.

If Outlook works fine here, then add-ins are the problem. Continue to the next fix to remove them.

Fix 2: Disable Faulty Add-ins

Faulty or outdated add-ins are one of the most common reasons Why does Outlook keep crashing on startup? To fix this:

  1. Open Outlook in Safe Mode.

  2. Go to File > Options > Add-ins.

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

  4. Uncheck all add-ins and restart Outlook normally.

  5. Enable add-ins one by one to identify the faulty one.

Once you find the problematic add-in, remove or update it.

Fix 3: Repair Outlook Data Files (PST/OST)

Corrupted PST and OST files are a major cause behind Why does Outlook keep crashing on startup? These files store your emails, contacts, and other mailbox data. When damaged, they cause Outlook to crash, freeze, or close unexpectedly.

Repair With or Without ScanPST.exe

Microsoft offers an inbuilt repair tool called the Inbox Repair Tool.

  1. Close Outlook completely.

  2. Go to:
    C:\Program Files\Microsoft Office\root\Office16
    (Path may vary depending on your Outlook version.)

  3. Locate SCANPST.EXE and run it.

  4. Browse your PST file and click Start.

  5. Allow the tool to scan and repair your data.

If ScanPST fails or the corruption is severe, you can use advanced tools like the SysTools Outlook Recovery Software to repair highly corrupted PST files without ScanPST.exe and restore emails, contacts, tasks, and calendars without data loss.

Fix 4: Reset the Navigation Pane

The navigation pane stores profile shortcuts and view settings. If these settings become corrupted, Outlook may refuse to start. Resetting it is a quick fix for Why does Outlook keep crashing on startup?

  1. Press Windows + R.

  2. Type outlook.exe /resetnavpane.

  3. Press Enter.

This resets the view settings and can immediately fix startup crashes.

Fix 5: Update Outlook and Windows

Using outdated versions of Outlook or Windows can also cause stability problems. This is another common explanation for Why does Outlook keep crashing on startup?

Steps to update Outlook:

  1. Open any Office app like Word.

  2. Go to File > Account.

  3. Click Update Options > Update Now.

Update Windows:

  1. Open Settings.

  2. Go to Windows Update.

  3. Install all pending updates.

Updating ensures bug fixes, improved stability, and better compatibility.

Fix 6: Create a New Outlook Profile

A corrupted Outlook profile can repeatedly crash the app at startup. Creating a new profile helps when you still face the problem even after repairing data files.

  1. Open Control Panel.

  2. Select Mail > Show Profiles.

  3. Click Add, and enter a name.

  4. Configure your email account again.

  5. Set your new profile as default.

Now check if Outlook starts without crashing.

Fix 7: Disable Antivirus Integration

Some antivirus applications interfere with Outlook’s MAPI and data files, which is another reason why Outlook keeps crashing on startup?

  1. Disable email scanning from your antivirus settings.

  2. Temporarily disable the antivirus (only for testing).

  3. Launch Outlook and check if it works.

If Outlook runs fine, add Outlook to the antivirus exclusion list.

Fix 8: Repair Microsoft Office Installation

If the installation files of Office are damaged, Outlook may keep crashing. This fix can help.

  1. Open Control Panel > Programs and Features.

  2. Select Microsoft Office.

  3. Click Change.

  4. Choose Quick Repair or Online Repair.

After repairing, restart Outlook and check.

Fix 9: Check for Large or Oversized PST Files

Oversized PST files slow down performance and can cause crashes. Microsoft recommends keeping PST size below 10–12 GB for optimal stability. Here’s what to do:

  • Archive old emails

  • Delete unnecessary items

  • Empty Deleted Items and Junk folders

  • Move older data to a separate PST file

This helps prevent future crashes.

Conclusion

If you are still stuck wondering Why does Outlook keep crashing on startup?, the primary reasons are usually data file corruption, add-in conflicts, profile issues, and outdated software. By following the solutions above—Safe Mode, disabling add-ins, repairing PST/OST files, resetting the navigation pane, updating Outlook, creating a new profile, and repairing Office installation—you can resolve the problem effectively. Always keep your Outlook updated and maintain clean, healthy PST files to prevent recurring issues.