How to install Microsoft oulook desktop App ?Resolve th issue , not able to install

Question

How to install Microsoft oulook desktop App ?Resolve th issue , not able to install

Answer 1

Hi @Selvakumar

Thank you for posting question to Microsoft Q&A forum.

May I ask what error it shows when you try to download Classic Outlook? Also, can you please provide you subscription type? (M365 subscriptions, LTSC 2016, 2019, etc.)

Have you tried downloading Classic Outlook via Install or reinstall classic Outlook on a Windows PC - Microsoft Support?

If not, please give it a try.

I look forward for your reply.

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Answer 2

Follow these steps to resolve installation issues and install Outlook desktop (classic Outlook for Windows):

1. Verify policies are not blocking installation
   1. Open the Local Group Policy Editor:
      • Press Windows key, type Edit Group Policy or press Windows + R, type gpedit.msc, and press Enter.
   2. Go to:
      • Computer Configuration → Administrative Templates → Windows Components → App package Deployment.
   3. Check these policies and set them to Not configured:
      • Prevent non-admin users from installing packaged Windows apps
      • Allow all trusted apps to install
   4. If these are enforced by organization policy, contact the admin to change them.
2. Check registry keys that can block Outlook installation
   1. Open Registry Editor (regedit).
   2. Verify the following locations for keys that might block MSIX/app installs:
      • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock
      • HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Appx
   3. Keys that affect installation:
      • BlockNonAdminUserInstall
      • AllowAllTrustedApps
      • AllowDevelopmentWithoutDevLicense
   4. If AllowAllTrustedApps is disabled, installation of the new Outlook MSIX fails. Install the Windows October cumulative update KB5031455 (or later November security update) for the OS version to fix this behavior.
3. Ensure firewall and proxy allow Outlook installer traffic
   1. Confirm that firewall/proxy is not blocking Microsoft Store and Office CDN endpoints used by Outlook installer:
      • https://res.cdn.office.net
      • https://res.cdn.office.net/nativehost/5mttl/installer/
   2. If blocked, request the network/security admin to allow these URLs.
4. Allow executables in the temp directory
   1. Classic Outlook downloads the installer to %TEMP% (usually under C:\Users\<username>\AppData\Local\Temp).
   2. Ensure security tools (AppLocker, antivirus, Group Policy, or other security software) are not blocking executables in this directory.
   3. Specifically, confirm that NewOutlookInstaller.exe is allowed to run.
5. Fix Delivery Optimization settings (Windows Update download mode)
   1. Open Registry Editor and go to:
      • HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\DeliveryOptimization
   2. For Windows 11:
      • If DODownloadMode is set to 100 (bypass), change it to 0 (default). Value 100 is deprecated and can cause installation failures.
   3. For Windows 10:
      • Set DODownloadMode to **0`.
6. Use alternative deployment methods if Microsoft Store is blocked
   • If Microsoft Store is blocked by the organization:
     1. Download the Outlook installer from the Office CDN using the provided .exe installer link.
     2. Open PowerShell 7 as Administrator.
     3. Navigate to the folder where Setup.exe is saved.
     4. Run:

                .\Setup.exe --provision true --quiet --start-*
        

   • If Microsoft Store is not blocked and the new Outlook is acceptable:
     1. Open PowerShell or Terminal.
     2. Run:

                winget install -i -e --id=9NRX63209R7B --source=msstore --accept-package-agreements
        

7. If Outlook still will not open after install
   • If Outlook installs but does not open or crashes, one proven resolution is:
     1. Uninstall Microsoft 365/Office completely.
     2. Reinstall Microsoft 365 from the subscription portal.
     3. Launch Outlook again and complete profile setup.

If the device is managed by an organization, some of these settings may be controlled centrally; in that case, contact the Microsoft 365/IT admin to adjust policies or perform the installation.

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References:

• Resolve installation issues in the new Outlook for Windows
• Troubleshoot issues you might see when you run Office 365 desktop setup
• Troubleshoot Outlook mobile issues
• What to do when Outlook will not open on my PC? - Microsoft Q&A
• Cannot download full desktop apps for Microsoft 365 (Family) - Microsoft Q&A
• AppInstall - Microsoft Q&A
• Microsoft Office apps for Mac quit unexpectedly - Microsoft Q&A
• Office running on OS 12.7.6 - Microsoft Q&A