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Error downloading embed file

Anonymous
2025-06-17T19:31:36+00:00

When sharing an embed file larger than 4 gigabytes with .jar extension, the file is not downloaded. And if you open devtools, the following message appears in the console: Download not allowed. The frame that initiates or instantiates the download is sandboxed, but the "allow-downloads" flag is not set. See https://www.chromestatus.com/feature/5706745674465280 for more details.

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  1. Anonymous
    2025-06-18T02:08:22+00:00

    Hello Otavio,

    Welcome to Microsoft Community.

    I understand you're encountering a download failure when attempting to share an embedded .jar file larger than 4GB. The error message in your browser's developer console—“Download not allowed. The frame that initiates or instantiates the download is sandboxed, but the 'allow-downloads' flag is not set”—indicates a browser security restriction related to sandboxed iframes. This issue is common when embedding downloadable content in environments that use sandboxed frames, such as Story Maps, embedded portals, or custom web apps.

    Kindly allow me to work you through the cause and possible solution Modern browsers like Chrome and Firefox enforce strict sandboxing rules for embedded content. If the iframe initiating the download does not explicitly include the sandbox="allow-downloads" attribute, the browser will block the download—even if the file is valid and accessible

    1. Host the File Outside the Sandbox

    If you cannot modify the iframe attributes, consider hosting the file on a direct-access page or using a download service that does not rely on sandboxed frames.

    1. Use Azure Blob Storage for Large Files

    For files over 4GB, Azure Blob Storage supports direct browser uploads and downloads using the JavaScript SDK. This method bypasses iframe limitations and is suitable for regulated environments

    1. Split the File or Compress It

    If feasible, split the .jar file into smaller chunks or compress it into a .zip archive to reduce size and avoid blocked formats

    1. Check NTFS Volume Limits

    If you're hosting the file on an NTFS volume, ensure there’s enough space for the uncompressed file. NTFS allocates space based on uncompressed size, which can cause errors even if compression is used

    Best Regards
    Sunday | Microsoft Community Support Specialist

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