Proxmox has released Proxmox Backup Server 4.2, a new update built on Debian 13.4 “Trixie” with refreshed packages, improved hardware support, and security updates from the newer base system. The release also moves to Linux kernel 7.0 as the stable default and includes ZFS 2.4 for storage environments that rely on ZFS-backed infrastructure.
The update covers backup organization, sync security, transfer performance, and S3-backed storage. For larger or distributed backup environments, the changes should make it easier to reorganize data, protect sync jobs, and monitor storage activity without adding extra manual steps.
Backup Groups and Namespaces Can Now be Moved Inside a Datastore
Administrators can now move backup groups and namespaces to different locations within the same datastore. This gives teams more room to reorganize existing backup structures without needing to rebuild or duplicate data in less direct ways.
The process also includes per-group locking to help maintain consistency. At the same time, backup data is being moved, which is useful when backup sets are active, large, or shared across multiple workloads.
Sync Jobs Gain Server-side Encryption and Decryption Options
Proxmox Backup Server 4.2 adds support for server-side encryption and decryption in sync jobs. Push sync jobs can now encrypt snapshots as they are sent to a remote datastore, which is useful when synchronizing backup data to a less-trusted remote Proxmox Backup Server instance.
Pull sync jobs can also be configured to decrypt snapshots that were encrypted on remote datastores. This gives administrators more flexibility when moving protected backup data between systems. Key management has also been brought into a single location, with tape and sync encryption keys now managed from the same centralized panel.
Parallel Sync Processing Improves Performance on Difficult Networks
Sync jobs can now process multiple backup groups simultaneously via the new worker-threads property. This change is intended to improve throughput, especially on high-latency networks where serial processing can limit transfer performance.
The update also helps address HTTP/2 connection limitations by allowing sync jobs to run concurrently across multiple groups. Logging has also been improved, with contextual prefixes for log messages and better visibility into push sync job activity. These additions should make it easier to understand what a sync task is doing and where issues may be occurring.
S3-Compatible Object Stores are Now Officially Supported as Backup Storage
Proxmox Backup Server 4.2 officially supports S3-compatible object stores as a backup storage backend. This gives S3-backed datastores a more formal role in Proxmox Backup Server deployments where object storage is part of the backup strategy.
Version 4.2 also adds request counters and traffic statistics for S3-backed datastores, providing administrators with a clearer view of activity and helping identify unexpected traffic early. The request counters are shown in the datastore summary, making it easier to check this information during routine monitoring.
Availability and Support
Proxmox Backup Server 4.2 is available for download as a full ISO image that can be installed directly on bare-metal systems using the guided installer. Existing installations can be upgraded through the standard APT package management system, and Proxmox Backup Server can also be installed on top of an existing Debian system.
Proxmox Backup Server 4.2 is released as Free/Libre and Open Source Software under the GNU AGPLv3 license. Enterprise support is available through Proxmox subscription plans, with pricing starting at EUR 560 per server per year. The subscription includes unlimited backup storage and clients, access to the stable Enterprise Repository, web interface updates, and certified technical support.
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