Description: When attempting to mount an image backup (.vhdx) via the UrBackup Web UI, the server daemon crashes immediately with a kernel-level general protection fault. However, manual command-line mounting using urbackupsrv mount-vhd works completely fine and successfully mounts the image via FUSE.
Steps to Reproduce:
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Navigate to a client’s image backup in the Web UI (e.g., a Windows client with
.vhdxbackups). -
Click Mount on an image backup point.
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The Web UI fails with
Mounting image failed. Please see server log file for details.and the server daemon dies.
Server Logs:
026-09-28 23:33:24: ERROR: Footer checksum wrong. Switching to header 2026-09-28 23:33:24: ERROR: Header and footer checksum wrong
Kernel log (dmesg):
[4764212.311016] traps: urbackupsrv[2015990] general protection fault ip:55c3d55ba37a sp:76a2957f1a30 error:0 in urbackupsrv[35937a,55c3d52ec000+7c4000]
Workaround: Running the manual command-line mount bypasses the crash entirely and successfully mounts the volume:
sudo urbackupsrv mount-vhd -f /path/to/backup.vhdx -m /mnt/test-restore
This confirms the underlying VHDX file and system helper tools (libguestfs-tools, FUSE) are healthy, pointing to a bug in how the Web UI wrapper/subprocess handles the mount call.
Environment:
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UrBackup Server Version: 2.5.38.0-1
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OS: Debian GNU/Linux (running in a VM)
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Storage backend: Local storage pool