# RabbitMQ v4.2.4 - Upgrade from ACDC 3.7.x

Use this procedure when upgrading RabbitMQ from version 3.11.x to version 4.2.x for Atlas Copco Data Communication 3.7.x or above.

## Requirements

- Erlang 26.2 or later (supported up to 27.x).

- Minimum 200 GB free disk space on the application server.

- Disk write speed of at least 200 MB/s.

- Windows Server 2022 or later.

## Prerequisites

- Stop Atlas Copco Data Communication.

- Empty all queues on ACDC Internal.

- Verify no Atlas Copco Data Communication processes are running before starting the upgrade.

Upgrade steps

1. Uninstall RabbitMQ, then uninstall Erlang.

2. Delete existing RabbitMQ data files (default location): C:\Users\Administrator\AppData\Roaming\RabbitMQ

3. If RabbitMQ or Erlang folders remain in C:\Program Files, delete them. If a folder cannot be removed, restart the server and delete it after reboot.

4. Download and install Erlang (recommended version for this upgrade: 27.3.4.8): https://www.erlang.org/patches/otp-27.3.4.8

5. Download and install RabbitMQ 4.2.x: https://www.rabbitmq.com/docs/install-windows#downloads

6. Complete RabbitMQ configuration by following the RabbitMQ setup section in the Atlas Copco Data Communication User Guide. Read RabbitMQ Setup for more information.

## Important information and verification

- Ensure the AtlasCopco_ACDC_ProtocolStore database state is preserved during the RabbitMQ upgrade. Changing the database type or deleting the database catalog/file will reset its state and may trigger reprocessing of a large number of controller messages.

- Make sure Erlang and RabbitMQ versions are compatible before starting Atlas Copco Data Communication.

- After installation, verify RabbitMQ service status and that all required ports and users are configured per the Atlas Copco Data Communication User Guide.

- Restart Atlas Copco Data Communication only after RabbitMQ is running and verified.