macOS sandbox restriction: ~/Library/Containers/com.microsoft.Excel not created or accessible on newer Macs (M4) – impact on Excel add-ins

Hi Indraneel L

Thank you for reaching out to the Microsoft Q&A Forum and for taking the time to describe your issue in detail.

I have reviewed your scenario and searched for related documentation, but I was unable to find any official Microsoft guidance that confirms or documents this specific behavior.

Please note that this is a public, peer-to-peer community forum. While moderators and community members can share general guidance and experiences, we do not have access to internal systems or a test environment to reproduce this issue. To avoid providing any potentially misleading or unsupported information, I recommend raising a support request directly with Microsoft for further investigation.

You can create a support ticket through the Microsoft 365 Admin Center by selecting Help & Support. Please note that this option requires the Global Administrator role, so you may need to ask your organization’s admin to submit the request on your behalf.

For further instructions, you can follow this guide: Get support - Microsoft 365 admin | Microsoft Learn.  

I understand this may not be the answer you were hoping for, and I appreciate your understanding.

Best regards,

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The available information does not document any supported or guaranteed use of ~/Library/Containers/com.microsoft.Excel for integrating with Excel, nor any specific change in behavior on newer Apple Silicon (including M‑series) that can be relied on for add‑in or companion‑app development.

From the provided context, only the following are supported and documented for troubleshooting and integration on macOS:

1. Office/Excel data and settings locations
   • Excel and other Office apps store user data and settings under ~/Library/Containers/com.microsoft.Excel and related Group Containers such as:
     • ~/Library/Group Containers/UBF8T346G9.Office
     • ~/Library/Group Containers/UBF8T346G9.ms
   • These locations are referenced only for troubleshooting (for example, deleting or moving them to reset Office/Excel when it fails to start or when encountering errors).
   • There is no guarantee in the documentation that ~/Library/Containers/com.microsoft.Excel is created at install time or that it is always accessible to external processes. Its creation and use are internal to Office and subject to macOS sandboxing.
2. Supported Excel add‑in models
   • For Excel add‑ins, the supported integration model is the Office JavaScript API (Office Add‑ins) and, for some scenarios, XLL or COM‑style add‑ins on Windows.
   • The documentation for Excel add‑ins focuses on:
     • JavaScript APIs and their limitations (for example, behavior when switching workbooks, coauthoring, and merge conflicts).
     • Security behavior such as blocking untrusted XLL add‑ins by default.
   • None of these supported models rely on direct file‑system access to ~/Library/Containers/com.microsoft.Excel.
3. Implications for the described scenario
   • Because the container path is not documented as a supported integration point, behavior such as:
     • The folder not being created until Excel is first run or until certain actions occur, or
     • The folder being inaccessible due to sandbox restrictions, is an internal implementation detail and cannot be depended on for a robust add‑in or companion‑app design.
   • Relying on this path for core functionality is therefore unsupported and fragile, especially across macOS versions and hardware generations (including newer Apple Silicon like M4).
4. Practical guidance based on the documented behavior
   • Treat ~/Library/Containers/com.microsoft.Excel and related container paths as internal implementation details, not as a public contract.
   • For Excel integration on macOS:
     • Use the Office JavaScript API for Office Add‑ins and design around its documented limitations (for example, workbook switching and coauthoring behavior).
     • Avoid assumptions about when or whether the Excel sandbox container directory exists or is accessible.
   • For troubleshooting Excel issues on macOS (crashes, startup failures, or errors), use the documented steps that involve ~/Library/Containers and Group Containers only as part of reset/repair workflows, not as a dependency for application logic.

Given the provided information, the behavior observed on newer Macs (including M‑series) should be treated as a consequence of macOS sandboxing and internal Office implementation, not as something that can be controlled or relied upon for add‑in functionality.

References:

• "Microsoft Excel has encountered a problem and needs to close" when starting Excel for Mac
• "Cannot use object linking and embedding" error in Excel 2016 for Mac
• Troubleshoot Excel add-ins
• Excel is blocking untrusted XLL add-ins by default
• Error message when using the Excel Add-in for Microsoft Forecaster 6.7: "Could not load an object because it is not available on this machine"
• XLOOKUP, FILTER NOT WORKING WITH EXCEL ON MAC 365. - Microsoft Q&A
• Are there known problems with Tahoe and Adobe - Microsoft Q&A
• Microsoft Office apps for Mac quit unexpectedly - Microsoft Q&A
• Can't access Microsoft support - Microsoft Q&A
• I have been using Excel for IPad for over a year and suddenly it has stopped working. - Microsoft Q&A
• Hosted macOS agents on Apple Silicon (GA)