Microsoft has admitted that an issue in Windows 11 24H2 could stop Outlook from starting. It has also been confirmed that Microsoft 365 Enterprise users will switch to the new Outlook in April 2026.
The Outlook [issue](https://learn.microsoft.com/en-us/windows/release-health/status-windows-11-24H2#3456msgdesc) turned up in the Release Health Dashboard for Windows 11 24H2 and is related to using Google Workspace Sync, a tool that allows a user to manage their Google Workspace data – emails, calendar entries, tasks – in Outlook.
Affected users will find that Outlook fails to start and Google Workspace Sync for Microsoft Outlook (GWSMO) cannot be uninstalled or reinstalled. According to Microsoft, an error message might be shown, saying: "Cannot Start Microsoft Outlook. Cannot Open the Outlook Window. The set of folders cannot be opened. An unexpected error has occurred. MAPI was unable to load the information service."
Microsoft said the issue is resolved in the latest version of Google Workspace Sync – 4.3.68.0 – but until it is installed, the company warned that a compatibility hold would be applied, meaning Windows 11 24H2 would not be offered. Last week, Microsoft [announced](https://www.theregister.com/2024/12/05/microsoft_windows_roll_out/) that it would be widening the rollout of the operating system update.
The company also directed users to contact Google Workspace Support if the hold was still encountered 48 hours after updating the application.
In addition to the issues with Outlook, Google Workspace, and Windows 11 24H2, Microsoft also announced via the Microsoft 365 Message Center that the time was running out for Outlook Classic.
"Starting April 2026, Microsoft 365 for Enterprise users will be switched from classic to new Outlook for Windows, with the option to revert back."
According to Microsoft, this will allow users to check out the new look and feel of New Outlook while still being able to fall back to Outlook Classic and the features they actually need to do their work.
Microsoft wrote: "New Outlook gives users the most modern experience with Copilot features, theming, and a wave of valuable time-saving features like Pinning and Snoozing mails."
The rollout applies to Microsoft 365 Enterprise licensees, although it can be stopped using a policy to hide the toggle. It also doesn't apply to perpetual licenses or on-premises accounts. Microsoft said: "When this change takes effect, if you choose to exclude users from the experience, you can use the following Admin policy to manage new Outlook migration: Admin-Controlled Migration to New Outlook. Later, this policy will also be available via Group Policy Objects (GPO), Cloud Policy, and Intune."
Microsoft has promised at least 12 months' notice of any changes to give customers time to prepare. That change is clearly on its way. ®