eM Client 11.0.1201.0 (MSIX) breaks iCalendar handling in Microsoft Outlook 2010

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eM Client 11 Beta: three MAPI/MMGA error dialogs after MSI-to-MSIX upgrade

Same issue here after the automatic upgrade from eM Client 10.4 (MSI) to 11.0.1201 (MSIX) on Windows 11 Pro 26H2, with classic Outlook (Microsoft 365, 64-bit). Since the upgrade, every Outlook add-in that uses Extended MAPI through the Windows MAPI stub (mapi32.dll) fails with 0x80004002 (E_NOINTERFACE). In my case TechHit SimplyFile no longer loads any folders and TechHit AccountCheck logs the same error. Outlook itself keeps working. What I found: The MSIX package registers itself as a pac…

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