Outlook is Having Trouble Starting? Here’s the Solution

“Click. Wait. Error.” Sometimes, instead of your inbox, you’re hit with the message: Outlook is having trouble starting. As a Microsoft 365 admin for 12+ years, I know how to resolve it. Therefore, I created this guide to educate users on why this happens and provide troubleshooting steps to fix it in minutes. Let’s begin our discussion. 

Why Outlook is Not Starting?

First, we’ll understand, this error often comes down to one of these issues:

• A corrupted Outlook profile
• Faulty add-ins are blocking the startup
• Damaged PST/OST data files 
• Outdated or conflicting updates in Office or Windows
• Navigation Pane corruption
• Improper closure of Outlook is leading to data file locks

Knowing the root cause makes troubleshooting much easier.

Outlook is Having Trouble Starting – Quick Steps

Fix the issue with these three instant checks:

#1. Safe Mode

Win + R > outlook.exe /safe

• If Outlook opens > go to Add-ins Fix.

#2. Reset Navigation Pane

Win + R > outlook.exe /resetnavpane

#3. Check the Microsoft Fixes Page, as they constantly updates its Outlook known issues page. If the error started after a Windows/Office update, this is where I always look first.

Related: How to Search an Email in Outlook?

How to Fix Outlook is Not Starting – Detailed Step-by-Step Instructions

Here are the step-by-step instructions for troubleshooting Outlook is having trouble starting error:

#Step 1. Are You Using New Outlook or Classic Outlook?

The fix depends on the version:

• New Outlook:
  • Try toggling back to Classic Outlook.
  • Check the Microsoft Q&A thread.
• Classic Outlook:
  • Continue with the steps below.

#Step 2. If Outlook Opened in Safe Mode

When Outlook works in Safe Mode, it means an add-in is breaking normal startup:

• File > Options > Add-ins
• Manage: COM Add-ins > Go
• Uncheck all add-ins > Restart Outlook
• Re-enable them one by one until the faulty one is found

#Step 3. If Outlook Still Won’t Open

Outlook depends on PST/OST files. When they’re corrupted, it won’t start, and it shows Outlook is having trouble starting:

Option A: Repair PST/OST with SCANPST

• Find SCANPST.EXE in your Office installation folder
• Run it > select your PST/OST file > Start to repair

Option B: Rebuild OST (Exchange / Microsoft 365 accounts)

• Close Outlook
• Go to: C:\Users\<mackjohn(username)>\AppData\Local\Microsoft\Outlook
• Delete the .ost file
• Restart Outlook.

#Step 4. If Data File Repair Fails

Sometimes the Outlook profile itself is broken:

• Control Panel > Mail > Show Profiles
• Click Add > set up account again
• Set the new profile as the default

#Step 5. If Issue Began After Updates

I’ve seen that Outlook is having trouble starting right after a Windows/Office update. Microsoft has acknowledged this in multiple articles. So, check:

• Outlook fixes/workarounds page
• Windows Update history for recent Office patches

#Step 6. Outlook is Not Starting – Advanced Fixes

If none of the above works, go advanced:

• Repair Office Installation
  • Control Panel > Programs and Features
  • Then go to Microsoft Office, and then click on Change.
  • Lastly, hit the Quick Repair or Online Repair.
• Use Microsoft SaRA Tool
  • Download the Support and Recovery Assistant
  • Run the Outlook troubleshooter

System File Checker (SFC)
Open Command Prompt as admin

Run: sfc /scannow

Also Read: How to Import PST to Office 365 without Outlook?

Author’s Verdict

“Outlook is having trouble starting” issue is resolved in this guide. All the proven steps and knowledge I covered in this guide. I guarantee, now you can easily resolve your Outlook is not starting error in minutes.