If a replication system domain has Replication Server 15.5 and later, then the system version and route versions in the replication system domain must be version 12.6 and later. With Replication Server 15.5, mixed-version environments containing versions earlier than 12.6 are not supported.

You can upgrade directly to Replication Server 15.5 from versions 12.6, 15.0, 15.0.1, and 15.2 and subsequent ESDs.

If any of the Replication Server version, the site version, and the route version are earlier than 12.6, you must upgrade Replication Server to version 12.6 or later, set site version to 12.6 or later, and upgrade routes to 12.6 or later, before you can install Replication Server 15.5.

You must upgrade the Adaptive Server containing the RSSD to version 15.0 or later, before you can install Replication Server 15.5.