ZIP Download Failures When Access to Files Is Denied

Product version: 11.1

Last modified: 08 January 2026

Problem

During File-Level Recovery, downloading recovered items as a ZIP archive may result in:

  • Corrupted ZIP files

  • ZIP files containing corrupted or incomplete data

  • Browsers show the download as successful even when FLR failed

This occurs when the source VM contains files or folders with denied access permissions, including:

  • Entire folders with denied rights

  • Folders containing a mix of accessible and inaccessible files

Background

The following explains the underlying behavior that causes ZIP files to become corrupted when access-denied items are included in an FLR download.

FLR job builds ZIP files on the fly while streaming content from the Transporter. When an access-denied item is encountered, the FLR process stops sending valid data. However, the browser still completes the download and finalizes the partially written file as a ZIP. Consequently, the presence of a single file with denied access causes the failure or corruption of the entire directory archive, rendering otherwise valid data within that set unrecoverable.

Solution

Follow the steps below to ensure successful FLR downloads:

  1. Before FLR, verify whether selected folders/files have the correct permissions.

  2. Where possible, avoid selecting parent directories known to contain files with restricted permissions. If a download fails due to corruption, attempt to narrow the selection to exclude the specific files or subfolders with denied Access Control Lists (ACLs).

  3. Ensure the user account used by the Transporter has 'Read' permissions for the requested files in the source VM.

  4. If the source VM uses Data Deduplication or Distributed File System (DFS), ensure that the corresponding features are installed on the operating system hosting the Transporter.

  5. Always verify the ZIP file after download.