Planning Your 23H2 to 24H2 Upgrade

If you’ve been running Azure Local on the 23H2 OS baseline, this post is for you. The 23H2 OS (version 25398.xxxx) is approaching its end of support in October 2025, and after that date, monthly security and quality updates stop. Your systems will continue to function, billing continues, and Microsoft Support remains available for upgrade assistance, but you’ll no longer receive security patches. That’s not a place you want to be for any length of time.

The good news is that the upgrade path from 23H2 to 24H2 is well defined, tested, and supported. The less good news is that it requires planning, and I’d rather you started that planning now than discovered in late October that you’ve left it too late.

Understanding the Upgrade Path

The upgrade from the 23H2 OS baseline to the 24H2 OS baseline is a solution upgrade, not a fresh deployment. This is important, because one of the pain points in the early days of Azure Stack HCI 23H2 was that moving from 22H2 to 23H2 required a full redeployment. The 23H2 to 24H2 path is a genuine in-place upgrade that preserves your existing configuration, workloads, and settings.

The process is managed through the Azure Local lifecycle management system in the Azure portal. You apply updates sequentially, so if you’re currently running an older 23H2 build, you’ll need to be on the latest 23H2 release (version 11.2510) before you can initiate the upgrade to 24H2. From 11.2510, the 24H2 update (12.2510) becomes available, and from there you can continue updating on the 24H2 release train.

This sequential approach is deliberate. Each step has been validated to ensure a clean transition, and skipping steps risks introducing inconsistencies that can cause problems later.

The Dell SBE Role

For Dell AX customers, the Solution Builder Extension plays a critical role in the upgrade process. The SBE delivers Dell-specific firmware and driver updates that are aligned with each Azure Local release. When you upgrade from 23H2 to 24H2, the SBE ensures that your Dell firmware and drivers are updated to versions that have been validated against the 24H2 OS.

This is one of the key benefits of running a Premier Solution . The combination of Microsoft OS updates and Dell SBE updates has been tested together through the CI/CD pipeline. You’re not applying a Microsoft update and then separately hoping that Dell’s firmware is compatible. They’ve been validated as a unit.

Before starting the upgrade, check the Dell support matrix for your specific AX node model to confirm SBE compatibility with the target 24H2 build. Dell publishes release notes for each SBE update that detail the firmware and driver versions included.

Pre-Upgrade Checklist

Here’s what I’d recommend working through before initiating the upgrade.

Verify your current build version. Make sure you know exactly what version you’re running. The upgrade path is sequential, and you need to be on the right starting point.

Check Azure Local health. Run the environment checker to validate that your cluster is healthy before starting. Upgrading a cluster that’s already in a degraded state is asking for trouble.

Review storage health. Ensure Storage Spaces Direct is healthy, with no degraded or missing drives, no rebuild operations in progress, and adequate free capacity. The upgrade process needs storage headroom to operate safely.

Backup critical workloads. This should go without saying, but make sure your backup and disaster recovery processes are current. Test a restore before you start the upgrade, not after something goes wrong.

Review the known issues list. Microsoft publishes known issues for each release. Read them. Some may be relevant to your specific configuration or workloads.

Schedule a maintenance window. The upgrade involves node-by-node processing with live migration of workloads between nodes. Plan for the time this takes, which will depend on the number of nodes and the volume of workloads running on the cluster. For a four-node cluster, expect several hours. For larger clusters, plan accordingly.

Coordinate with your Dell support team. If you have Dell ProSupport, let them know you’re planning an upgrade. They can review your environment and flag any specific considerations for your node model and SBE version.

What to Expect During the Upgrade

The upgrade process works node by node. Workloads are live migrated off the first node, the OS upgrade is applied, the node reboots, it’s validated, and then the process moves to the next node. This is the same pattern used for regular cumulative updates, just with a larger scope of change.

During the upgrade, your workloads continue to run. The live migration process moves VMs between nodes transparently. There may be brief interruptions to VM connectivity during migration, depending on your network configuration and workload characteristics, but for the majority of workloads this is seamless.

After the upgrade completes on all nodes, the cluster will be running on the 24H2 OS baseline. From here, you’ll receive updates on the 24H2 release train, following the monthly versioning model that I covered last December.

Don’t Leave It to the Last Minute

My strong recommendation is to start planning now, and if possible, execute the upgrade before the end of support date. Running an unsupported OS baseline means no security patches, which in today’s threat landscape is an unacceptable risk for production infrastructure.

If you have a non-production or test cluster, upgrade that first. Get familiar with the process, validate that your workloads behave correctly on 24H2, and then apply the lessons learned to your production upgrade.

The 24H2 OS baseline brings genuine improvements in performance, security, and manageability. The upgrade is well worth doing on its merits, and the approaching end of support for 23H2 gives you the nudge to prioritise it. Get it on the calendar.