outlook new not opening since morning

Hello avinash saigaonkar,

Thank you for reaching out, and I'm sorry for the trouble this has caused. The sudden disappearance of the "Try the new Outlook" toggle, along with the automatic switch back to Classic, usually points to one of a few things: a configuration change at the registry level, an update to Exchange Online policies, or a corruption in the local application state. The good news is that we can work through this step by step to get things back in order.

Please try the following in sequence:

1. Verify the New Outlook installation

Let's first check whether the New Outlook app is still installed and functional on your device.

• Press Windows key + R to open the Run dialog.
• Type olk.exe and press Enter.

If New Outlook opens successfully, the app itself is intact, and only the toggle in Classic Outlook is hidden. If it doesn't launch, the app may have been removed and will need to be reinstalled from the Microsoft Store.

2. Check organizational mailbox policies (for Work or School accounts)

If your account is managed by an organization, your IT admin may have updated the OWA Mailbox Policy overnight to restrict access to New Outlook. It's worth a quick check with your admin to confirm whether any recent policy changes were made on their side.

3. Repair or reset the app Go to Settings > Apps > Installed apps > Outlook (new) > Advanced options

Try Repair, then Reset if needed.

4. Update Classic Outlook In Outlook, go to File > Office Account > Update Options > Update Now.

Please try these steps in order, and the toggle should reappear once the underlying cause is addressed.

If there's anything else I can help clarify or walk you through, please don't hesitate to reach out. And if this answer was helpful, kindly mark it as accepted so it can guide others in a similar situation.

Warm regards,

New Outlook likely isn’t available because classic Outlook can’t show the toggle, or classic Outlook isn’t installed.

Try these steps:

1. Confirm classic Outlook is installed
   • Open Start and look for Outlook (classic).
   • If it isn’t there, install classic Outlook using the steps in “You can't open classic Outlook on a new Windows PC”.
2. Check why the toggle is missing in classic Outlook
   • Ensure Windows is Windows 10 build 1809 (17763) or higher.
   • Ensure Outlook is on a supported update channel: Current Channel, Monthly Enterprise Channel, or Semi-Annual Enterprise Channel (preview).
   • Make sure the profile doesn’t only contain unsupported account types (for example, POP or on‑premises Exchange only).
3. Check if policy or registry hides the toggle
   • Registry: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General
     • If HideNewOutlookToggle is set to 1, change it to 0 and restart Outlook.
   • If managed by an organization, an admin should check the Microsoft 365 Apps admin center policy “Hide the "Try the new Outlook" toggle in Outlook” and disable it if enabled.
4. If the toggle still doesn’t appear
   • Try signing in on another PC where new Outlook works to see if the toggle appears there.
   • If not, contact Microsoft Support and include the .etl logs from %Temp%\Outlook Logging to help diagnose why the toggle is missing.

References:

• Resolve deployment issues in the new Outlook for Windows
• Toggle out of the new Outlook for Windows
• You can't open classic Outlook on a new Windows PC