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Ensure that all nodes have the same X-Road software version (at least version 7.4.0) and PostgreSQL version is 12. All Red Hat packages are updated.
If necessary, update the cluster, following instructions in [1], section 7.
Pause the database and configuration synchronization on the secondary nodes ([1], section 7.2.1).
Connecting a hardware security module (HSM) to a new server may require additional steps that are not covered by these instructions. Check the HSM documentation and verify that it supports RHEL 8.
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