Switching to Outlook Classic Fails

Question

Switching to Outlook Classic Fails

Vince Hannant 0

When I select the Go To Classic button, I skip feedback and then get an error message, "The operation failed due to an installation problem. Restart Outlook and try again. If the problem persists please re-install" I have followed this advice, including uninstalling Office 365 and completely re-installing but the problem remains. Any guidance please?

Vince Hannant 0 Reputation points

2025-12-10T20:58:06.58+00:00

Not sure if this helps, but I get the same error message if i try to open outlook in safe mode. I cannot open it in safe mode regardless of version

2 answers

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Vince Hannant 0 Reputation points

2025-12-10T20:58:06.58+00:00

Not sure if this helps, but I get the same error message if i try to open outlook in safe mode. I cannot open it in safe mode regardless of version

Answer 1

If you are encountering an error message stating, "The operation failed due to an installation problem. Restart Outlook and try again. If the problem persists please re-install," when trying to switch to Classic Outlook, there are several troubleshooting steps you can consider:

Check Installation Issues: Ensure that there are no security policies or software blocking executables from running in the user's temp directory. This includes checking for any security programs like AppLocker or Anti-Virus that may interfere with the installation process.
Firewall and Proxy Settings: Make sure that your firewall or proxy settings are not blocking access to the necessary Microsoft services. This can prevent the download and installation of updates required for Outlook to function properly.
Compatibility Settings: Verify that Outlook is not running in compatibility mode. Right-click on Outlook.exe, go to Properties, and check the Compatibility tab to ensure that the option for "Run this program in compatibility mode for" is unchecked.
Registry Settings: If you have modified any registry settings, ensure that they are correct. For instance, the HideNewOutlookToggle registry key should be set appropriately if you are trying to manage the visibility of the toggle in Classic Outlook.
Reinstall: Since you have already reinstalled Office 365, ensure that you are completely removing all components before reinstalling. You may want to use the Microsoft Support and Recovery Assistant to help with this process.

If the problem persists after trying these steps, consider reaching out to Microsoft Support for further assistance, providing them with any relevant logs or error messages you have encountered.

Answer 2

Gabriel-N 9,950 Microsoft External Staff Moderator

Dear Vince Hannant

Thank you for reaching out to the Q&A forum.

To better assist you, could you please share more details about the steps you’ve tried besides uninstalling and reinstalling Office?

Additionally, have you tried downloading and installing Classic Outlook directly instead of switching from the new Outlook? You can follow the instructions as well as the download link here: Install or reinstall Classic Outlook on a Windows PC

From my research, there’s an official document about installation issues: Resolve Installation Issues in the New Outlook for Windows - Outlook | Microsoft Learn. While it’s not exactly your scenario, there’s a chance your device might be managed by your company, and certain registry keys set by Group Policy or non-Microsoft tools could block MSIX package installation.

In this document, they mention changing registry keys and other methods. However, please note that changing registry keys is risky and requires admin privileges. Since you mentioned you can reinstall Outlook, I recommend trying the Classic Outlook installation from the link above first to see if that resolves the issue.

Please try the suggestion and share your feedback.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread

Vince Hannant 0 Reputation points

2025-12-10T15:56:16.1333333+00:00

Thank you - I had tried reinstalling outlook classic from that link, but the link does res-install all of office. The install worked but did not solve the problem. Will look at your document link now. I am a sole trader so have the admin rights for my account.
Vince Hannant 0 Reputation points

2025-12-10T16:02:29.7866667+00:00

I can't find any group policy settings - I don't think I have them set up
Gabriel-N 9,950 Reputation points Microsoft External Staff Moderator

2025-12-11T09:39:48.8666667+00:00
Dear Vince Hannant

Thank you for providing the details, and apologies for the late reply.

Could you please confirm whether you can still open the New Outlook app, or is it completely failing to launch?

Also, based on what you shared, I’d like to know:

Your Office license type (Microsoft 365 subscription or standalone)

The Office version installed

Your Windows version.

To check this, please go to Control Panel > Programs > Uninstall a program, and take a screenshot showing the installed Microsoft Office products. I’d like to confirm if you have Microsoft 365 and/or Microsoft Outlook 2016 listed.

After that, please try these methods:

Online Repair: In the same Uninstall a program window, right-click Microsoft 365 (and Microsoft Outlook 2016 if present), then select Change > Online Repair. Once the repair completes, check if the issue is resolved.

Create a New Outlook Profile: Open Control Panel and set View by: Small icons > Click Mail (Microsoft Outlook) > Click Show Profiles > Add, name it (e.g., TestProfile), and click OK.
Set up your email account in the new profile. Under Always use this profile, select the new one, then click Apply > OK.
Relaunch New Outlook and try switching to Classic again.
For detailed steps, please refer to this link: Create an Outlook profile - Microsoft Support

Launch Classic Outlook by navigating to: C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE and double-click to open Classic Outlook and see if it works.

Registry Key Edit: Before proceeding, please export the key as a backup since editing the registry can cause issues if done incorrectly.
Right-click the "Preferences" folder in regedit, select Export, and save it somewhere safe.
Close Outlook completely. Press Windows Key + R, type regedit, and press Enter. Navigate to: Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences. Look for UseNewOutlook on the right:
If it exists, double-click and set Value data to 0.
If it doesn’t exist, right-click > New > DWORD (32-bit) Value, name it UseNewOutlook, and set it to 0.
Close Registry Editor, restart your computer, and try launching Outlook again.

Please try these steps and share the requested information in a private message so I can assist further.
Gabriel-N 9,950 Reputation points Microsoft External Staff Moderator

2025-12-12T09:01:14.7266667+00:00

Dear Vince Hannant

May I know if you have got any chance to check my reply? Please feel free to share more detailed information to us and it will be very helpful for us to better work out this issue.

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Switching to Outlook Classic Fails

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