> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/products/cc-hardware/controllers/controller-6000/configure/controller-6000-revalidate-certificate.md).

# Revalidate Certificate

Revalidate Controller 6000 certificates after a reset or Linux migration.

## What "Revalidate Certificate" does

The **Revalidate Certificate** override is used to restore secure communication between a Gallagher controller and Command Centre when a **certificate mismatch or invalidation** occurs.

This override forces the system to **re-authenticate the controller's certificate**, allowing it to come back online securely.

***

## When and why to use it

### 1. After DIP Switch 2 is turned ON

Turning on DIP Switch 2 causes the controller to **drop its configuration**, including pinned certificates. When the controller reconnects to the server, the certificate no longer matches, triggering an **"Authentication failed - invalid certificate"** alarm. In this case, you **must** apply the Revalidate Certificate override to bring the controller back online.

### 2. During Controller Reset or Firmware Upgrade

When performing a factory reset or upgrading the controller firmware, especially with **DIP Switch 2 and 8 procedures**, the certificate may be invalidated. Revalidating ensures the controller's certificate hash is updated and matches the Command Centre database.

See [DIP Switch 8 Recovery](/knowledge-hub/products/cc-hardware/controllers/controller-6000/troubleshoot/controller-6000-dip-switch-8-recovery.md).

### 3. After Telemetry or Diagnostic Service changes

If the **Diagnostic Service Site (DSS)** certificate is regenerated, or the controller is power-cycled, the certificate hash may change. Revalidating updates the hash in the **AssociatedCertificate table** and ensures telemetry can resume securely.

### 4. When invalid certificate alarms appear in Command Centre

If you see alarms in Command Centre related to invalid certificates:

1. Open the controller's properties in the **Hardware** window.
2. Go to the **Status and Overrides** tab.
3. Select **Revalidate Certificate** from the dropdown.
4. Click **Override Now**.

***

🔗 **Related**

* [Certificates and Keys](/knowledge-hub/products/cc-hardware/controllers/controller-6000/reference/controller-6000-certificates-and-keys.md). The certificate and key reference.
* [DIP Switch 8 Recovery](/knowledge-hub/products/cc-hardware/controllers/controller-6000/troubleshoot/controller-6000-dip-switch-8-recovery.md). Where revalidation is required after recovery.
* [FAQs - Upgrading Factory WinCE Controller 6000s](/knowledge-hub/products/cc-hardware/controllers/controller-6000/configure/controller-6000-faqs-upgrading-factory.md). Q2 explains why revalidation is needed after DIP Switch 2.


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