Microsoft has announced a security‑driven adjustment to its AutoUpdate mechanism. Ryan Haning, Product Manager for Microsoft 365 for Mac, explains that the change concerns the way the ManifestServer preference is applied on client devices.
From Microsoft AutoUpdate (MAU) 4.79 onwards, any ManifestServer URL or local‑folder path configured on an unmanaged device will be ignored. Only devices under management, via an MDM or similar solution, will evaluate a custom ManifestServer setting.
By restricting ManifestServer configurations to managed contexts, organisations can prevent unauthorised or misconfigured local update manifests from being applied. In turn, this helps to safeguard the integrity of Office updates and reduces the risk of inadvertently deploying malicious or outdated software.
Moreover, IT teams who rely on custom update sources must ensure all relevant Macs are enrolled in a device‑management platform such as Microsoft Endpoint Manager or another supported MDM. Any ManifestServer preferences left in a local configuration on unmanaged machines will no longer take effect, which could disrupt update workflows if not addressed.
Furthermore, Microsoft recommends that IT administrators should begin by auditing their environments to identify any locally configured ManifestServer preferences. They should also ensure that every Mac requiring specific ManifestServer configurations is enrolled in an approved device‑management solution, and communicate this change to all stakeholders by updating internal guidance and adjusting deployment processes accordingly. The company writes:
Next steps
- Review your organization"s update management settings and determine if the ManifestServer setting is currently being used locally.
- Ensure all devices requiring specific ManifestServer configurations are enrolled in a device management solution.
- Communicate this change to your team and plan any necessary adjustments to your deployment processes.
As mentioned previously, this change takes effect with Microsoft AutoUpdate (MAU) version 4.79. For full technical details and configuration instructions, you may want to consult Microsoft’s documentation here.