How to fix
Outlook is already running error
on Windows

So when I try to launch Outlook (I'm using Windows), it says that it's already running, although it isn't. How can I fix that?

When you attempt to open Outlook only to be faced with a message telling you that Outlook is already running, that can indeed be frustrating. Even though Outlook isn't visible on your screen, this message will continues to display, leaving you hanging and unable to access your email or calendar. Many Windows users have experienced this common trouble that can destroy their day, which has often plagued countless Windows users.

It is Microsoft's influential email and productivity software and part of the Microsoft Office suite. With the intention of bringing together one's emails, calendar, contacts, and tasks in one place, Outlook boasts features such as search functionality, cloud connection with OneDrive, and impressive security options that endear it to its users for both work and personal use.

Why does the Outlook is already running error happen?

The Outlook is already running error shows up when Outlook doesn’t fully close, leaving a hidden process active in the background. Windows detects this and blocks you from opening a new session, even if you can’t see the app. This might happen because of a crash, an unexpected shutdown, or a clash with another program running on your system.

This Outlook is already running error is more than just a nuisance - it stops you from using Outlook when you need it. Whether you're waiting for an important message or looking at your calendar, this glitch can disrupt your work. It affects several versions of Outlook and Windows, including Windows 11, so it's widespread.

What's next?

There are straightforward ways to tackle the "Outlook is already running error," from simple checks to more thorough fixes. You’ll find detailed solutions below. For a quick and easy option, the [d1] system repair tool can automatically resolve this and other Windows issues that might be behind the problem.

1. Close Outlook using Task Manager

This method forces any hidden Outlook process to shut down.

• Press Ctrl + Shift + Esc to open Task Manager.
• Click More details if needed.
• Look for Microsoft Outlook in the list.
• Right-click it and select End Task to stop it completely.
• Try opening Outlook again.

2. Check for multiple Outlook instances

Sometimes, multiple unseen instances confuse Windows, so closing down these instance would address te problem.

• Open the Task Manager.
• Scroll through the Processes tab carefully.
• Look for more than one entry named Microsoft Outlook.
• End each one by right-clicking and selecting End Task.

3. Start Outlook in Safe Mode (and disable ad-ins)

• Press Win + R to summon the Run dialog.
• Type outlook /safe and hit Enter.
• If Outlook launches, add-ins may be causing the issue.
• Deactivate them by navigating to File > Options > Add-ins, selecting COM Add-ins, and clicking Go. Disable all add-ins and restart Outlook normally to see if the problem is resolved.

4. Repair Outlook through Control Panel

• Open Control Panel.
• Select Programs > Programs and Features.
• Select Microsoft Office and click on Change.
• Choose the option for Online Repair and click Repair.
• Follow the prompts to finish the process.

5. Update Windows and Outlook

Update Windows

• Type Updates in Windows search and hit Enter.
• If updates are available, click Install updates.
• Otherwise, click Check for updates.
• If optional updates are available, install them as well.
• When all the update processes are complete, restart your system.

Update Outlook

• Open Outlook and click on the File menu.
• Choose Office Account or Account (the option may vary depending on your version of Outlook).
• Under the Product Information section, you will find an Update Options button. Click it and select Update Now.
• Outlook will check for and install any available updates.
• Once the update is complete, restart Outlook to ensure the changes take effect.

6. Disable conflicting antivirus software

By disabling third-party software, you can avoid conflicts with Outlook.

• Open your antivirus program.
• Look for an option to turn off real-time scanning.
• Try launching Outlook again.
• If it works, add Outlook as an exception in your antivirus settings.

7. Clear temporary files manually

Temporary files can pile up and interfere with Outlook, so try clearing them:

• Press the Win + R key together, type %temp% and press Enter.
• A folder will open with lots of files - select all by pressing Control + A key, then press Delete.
• Empty the Recycle Bin afterward.
• Restart your PC and open Outlook.