> For the complete documentation index, see [llms.txt](https://docs.trilio.io/openstack/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.trilio.io/openstack/about-trilio-for-openstack/t4o-6.x-release-notes.md).

# Release Notes

## 6.2.1

#### Release Date : 21st Aug'2026

### What's New?

1. New Qualifcation
   * Qualification support for RHOSO18.0-FR6 (18.0.21).
   * Qualification support for Canonical Jammy.
   * Qualification support for Sunbeam Canonical 2024.1 (Caracal) on Noble.
   * Qualification support for MOSK & OS Helm.
2. New Features
   * Unified import and reassign operator.
   * Tenant chargeback csv download.
   * Upgrade from 5.x to 6.2.1 on Kolla-Ansible.
3. Enhancements
   * **Nova Server Group Preservation** — the Nova server group each protected instance belongs to is now captured with every Snapshot and reapplied when the instance is restored, preserving affinity / anti-affinity placement across restore, migration and disaster recovery. Selective Restore lets you choose the target server group per instance; One Click Restore reuses the captured group automatically. See [Features](/openstack/about-trilio-for-openstack/features.md#nova-server-group-preservation) for details.
4. Bug Fixes
   * VM restored via selective restore after deletion of original VM automatically becomes the member of the workload.
   * Selective restore fails with error : you cannot attach a port multiple times.
   * Pre-created port IP not attached to the VM from selective restore attempted from API.
   * Misleading error message in selective restore Failed restoring snapshot: Timeout waiting for the instance to boot from volume even after waiting for 4 minutes.
   * Selective restore fails with error that port is still in use.
   * NFS mount hangs on 6.2 release.
   * Unauthorized Backup Operations Are Not Properly Rejected.
   * Snapshot-create API blocks wlm-api worker for full snapshot duration → scheduled backups fail with "Proxy Error" under load.
   * Unexpected Workload VM Membership Loss.
   * API for usage report.
   * s3fuse segment cache unbounded in aggregate → repeated OOM kills of s3vaultfuse → mount outages fail snapshots.
   * Preserve Nova Server Group Metadata During RHOSP16.2 to RHOSO18 VM Migration/Restore

### Known Issues

1. Snapshot mount fails on Kolla Ubuntu Flamingo.
2. Horizon: snapshot/restore cancel buttons broken; snapshot row click hangs on `Loading`. This issue is intermittent.
   * Workaround:
     * Refresh the page and try cancel operation again.
3. 504 gateway timeout error in bulk deletion of error state snapshot from UI.
   * Workaround:
     * Delete multiple snapshots (*in loop*) from CLI using a script which will delete 1 snapshot at a time.
4. Retention failing intermittently with NFS V4.

## 6.2.0

#### Release Date : 30th April'2026

### What's New?

1. Support for Kolla Epoxy (2025.1) & Kolla Flamingo (2025.2) \[For Rocky 9 & Ubuntu 24.04].
2. **Dynamic Mount Service (DMS)** — backup targets are now mounted per-job and reference-counted across controller and compute nodes, replacing the previous per-backup-target container model. See [T4O Architecture](/openstack/about-trilio-for-openstack/triliovault-for-openstack-architecture.md#dynamic-mount-service-dms) for an overview.
3. S3 backup-target credentials are now retrieved from OpenStack Barbican at mount time through the new `secret_ref` field on the backup target, instead of being supplied in configuration.

### Known Issues

1. Snapshot mount fails on Kolla Ubuntu Flamingo.
2. Incremental backups fail after upgrading to T4O-6.2.0 when using immutable Ceph S3 backup target (mainly for image booted instances).
   * Workaround:
     * Initiate a Full snapshot.
3. Workload Reset operation fails to cleanup the volume snapshots.
4. Workload Import getting stuck.
5. Horizon: snapshot/restore cancel buttons broken; snapshot row click hangs on `Loading`. This issue is intermittent.
   * Workaround:
     * Refresh the page and try cancel operation again.
6. 504 gateway timeout error in bulk deletion of error state snapshot from UI.
   * Workaround:
     * Delete multiple snapshots (*in loop*) from CLI using a script which will delete 1 snapshot at a time.
7. Retention failing intermittently with NFS V4.