Microsoft’s workaround for classic Outlook issues after Windows 11 update

The latest KB5074109 update for Windows 11 causes the classic Outlook app to crash and lose emails, and there’s a risk of data loss if PST or OST files are stored on cloud-backed storage! You can read more about it on this Microsoft support page.

If classic Outlook crashes due to the issue caused by update KB5074109, you must close the email program via Task Manager and restart it. This may result in sent emails not appearing in the Sent Items folder.

Microsoft writes:

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