# Upgrade Prerequisites

In order to use the external WebAPIs or external publishing, a valid Atlas Copco Data Communication WebAPI Services Unify license must be applied.

RabbitMQ must be configured to use version 2 (v2) of the queues before starting the Atlas Copco Data Communication service.

When upgrading or installing the latest , make sure RabbitMQ prerequisites are set before starting. If these were already set in the previous version, you can skip the steps below.

## RabbitMQ

When upgrading Atlas Copco Data Communication from a version lower than 3.5.0, the following prerequisites must be configured in RabbitMQ.

1. Ensure all non-meta data queues on the ACDC-Internal virtual host are empty.

2. Stop the RabbitMQ service and navigate to the RabbitMQ folder. The default path is C:\Users\{username}\AppData\Roaming\RabbitMQ. Adjust the path if you have a custom installation.

3. Locate or create the configuration file for RabbitMQ: rabbitmq.conf.

4. Add the following configuration setting to the file.

   `# Set the default version for classic queues`

   `classic_queue.default_version = 2`

   `# Use '2' for classic queues (v2)`

5. Restart the RabbitMQ service.

6. Apply a policy to the ACDC-InternalServices virtual host to ensure its queues run exclusively on version 1 (v1):

   1. Open the Admin tab in RabbitMQ.

   2. Select Policies.

   3. Add or update a policy using the following settings:

      - Virtual host: ACDC-InternalServices

      - Name: v1policy

      - Apply to: Queues

      - Definition: queue-version = 1

7. Delete all queues for the controllers on the ACDC-Internal virtual host before starting the Atlas Copco Data Communication service.