Comet Backup agent fails to back up the home directories (/var/directory) of the system user on Linux

Symptoms

• After upgrading the Comet Backup client from version 26.4.4 to version 26.7.0, backup jobs on Linux Debian (or similar distributions) complete with warnings, omitting specific directories.
  The job log displays the following warning message:

  CONFIG_TEXT: Warning for ROOT/var/directory: Couldn't check directory contents: Open: open /var/directory: permission denied

  Note: /var/directory represents any directory in the /var directory.

• The problem persists even though the target directory permissions allow read access, and the backup process (backup-tool) is verified to be executing explicitly as the root user.

Cause

This is a Comet Backup bug with ID COMET-59990, which has been fixed in Comet 26.7.1 Janus.

Starting in the 26.5.x Voyager branch, aggressive system-level sandboxing features were introduced or modified in the backup agent daemon. The client incorrectly identifies paths like /var/directory as a default local home directory belonging to a built-in Linux system user. If files or directories within that location were created or modified by a different user account, the agent's sandboxing mechanism takes effect prematurely, restricting the root-run backup process from accessing the path and throwing a permission denied error.

Resolution

Upgrade Comet Backup to the latest version:

1. Download Comet Backup either from the Comet Account Portal or using an API request.

2. Run the installer:

   # sudo apt install ./cometd_{release_version}.deb

3. Deploy the update to the agent by starting a bulk upgrade campaign, or manually from the device's Actions menu.