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tomflow15's avatar
tomflow15
Copper Contributor
Jun 08, 2026

Outlook 16.109.3 crashes on launch on macOS 26 (Tahoe beta) - UTI Info.plist regression

Environment:

  • macOS 26.5.1 Build 25F80 (Tahoe beta)
  • - Microsoft Outlook 16.109.3 (build 26053122)
  • - MacBook Air Mac14,2 arm64, 16GB

Issue:

Outlook crashes immediately on every launch. Occurs on clean install with no profile. Tested two builds (26053122 and 26051019) - both crash identically.

 

Root cause from system logs:

macOS 26 has tightened UniformTypeIdentifiers enforcement. Outlook's Info.plist is missing explicit declarations for 12+ com.microsoft UTI types. On every launch:

 

"UniformTypeIdentifiers: Type 'com.microsoft.DataObject' was expected to be declared and exported in the Info.plist of Microsoft Outlook.app, but it was not found."

 

Same error fires for: com.microsoft.Embedded-Object, EMF-Plus, GIF-Office-Art, Ink-Serialized-Format, JFIF-Office-Art, Link-Source-Descriptor, Object-Descriptor, Embed-Source, PNG-Office-Art, Office-Drawing-Drag-Drop-Format, Office-Drawing-Shape-Format.

 

Secondary error: /private/var/db/DetachedSignatures does not exist on macOS 26, causing an SQLite open failure in libsqlite3.

 

Workaround: None. Outlook Web only until a fix ships.

 

Ask: Please update Outlook's Info.plist to explicitly declare all com.microsoft UTI types to comply with macOS 26's stricter enforcement. This will affect all Microsoft 365 Mac apps when macOS 26 ships publicly this fall.

1 Reply

  • StephenAB's avatar
    StephenAB
    Copper Contributor

    I also have an Outlook error which appears to relate to latest update to Tahoe

    Outlook font issues since Tahoe 26.5.1. upgrade

     

    I’m using Outlook 16.110. Since the upgrade (yesterday) outlook is presenting difficulties with the fonts.

     

    It is presenting in Bold (even though set to normal) will not change to - say italics - if I change to Aptos it sticks there and will not switch back to my default font.

     

    I have tried a number of actions to resolve the problem:

     

    resetting the cache using terminal

    deleting the fonts and reinstalling

    using the web (same problem)

     

    The legacy version works OK but is not ideal

     

    Any ideas much appreciated