There is no fix available, but you can always revert to an older version.

Microsoft is looking into a newly identified issue in classic Outlook that prevents users from opening certain encrypted ...

You may see this error because the Microsoft 365 encryption service cannot verify your identity or check if you have permission to view the message. This is not ...

Microsoft is investigating a known issue that triggers Outlook errors when opening encrypted emails sent from other organizations. According to a recently published support document, this issue ...

Microsoft is investigating a bug preventing recipients from opening encrypted emails in classic Outlook after a recent update. This known issue affects users who try to open messages encrypted with ...

PCWorld reports that Microsoft has confirmed a bug in classic Outlook version 2511 preventing users from opening encrypted emails. This issue significantly impacts business users and organizations ...