> For the complete documentation index, see [llms.txt](https://docs.helmut.de/helmut4-releases/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.helmut.de/helmut4-releases/getting-started/upgrade-guide/helmut4-server/server-host-update-and-upgrade.md).

# Server Host Update & Upgrade

## Overview

Operating system and distribution updates, as well as version upgrades, are the responsibility of the customer or the hosting provider.

For supported distributions, refer to the [system requirements](/helmut4-releases/getting-started/tech-specs/helmut4-server.md).

### Updates

Always update and validate the staging system before applying updates to the production server.

### Regression Testing and Grace Period

Before updating production, apply the update to the staging system and allow a defined grace period for regression testing.

During this period, verify all critical workflows and dependencies, including:

* integrations and external services;
* scheduled jobs and automations;
* backups and restore procedures;
* monitoring and alerting; and
* user-facing functionality.

Testing should reflect normal operating conditions and, where applicable, expected peak loads.

Apply the update to production only after:

* all critical workflows have passed testing;
* no unresolved high-impact issues remain;
* the staging system has remained stable throughout the grace period; and
* a rollback or recovery plan has been confirmed.

If testing identifies an issue, postpone the production update, resolve the issue, and repeat the validation process. Record the test results and obtain the required approval before proceeding.

### Upgrades

Schedule upgrades outside production hours whenever possible. We generally recommend deploying a new virtual machine (VM) rather than upgrading the existing operating system in place. This approach provides a clean rollback path and preserves the existing environment in case problems occur.

After the new VM is running successfully, restore the Helmut configuration through the application preferences.

For more information, refer to [Backup & Restore](/helmut4-releases/helmut4-components/helmutfx/preferences.md#backup-and-restore)

#### Cluster Upgrade

When upgrading from an older Ubuntu version, such as Ubuntu 20.04 LTS, to a newer version, such as Ubuntu 24.04 LTS, we recommend initially creating a new set of VMs.

Configure the new VMs, restore the Helmut configuration, and complete the required regression testing and grace period before switching production traffic.

Once the new cluster has been validated:

1. Update the DNS entry to direct users to the new cluster.
2. Monitor the new environment closely after the DNS change.
3. Keep the previous cluster available until the new environment has been confirmed stable.
4. If a critical issue occurs, revert the DNS entry to the previous cluster and investigate before attempting the cutover again.