Upgrading directly to Message Queue 4.2 from earlier versions is not supported on the Windows platform, but Version 4.2 can coexist with Versions 3.6 and 3.7 in different locations on the same system. How you treat existing Message Queue installations when installing Message Queue 4.2 depends on the previously installed version:
If you have an existing installation of Message Queue 3.5 or earlier, you should uninstall it (or upgrade it to Version 3.6 or later), using the uninstallation procedures described in the edition of the Message Queue Installation Guide corresponding to that version, before installing Message Queue 4.2.
If you have an existing installation of Message Queue 3.6 or 3.7, you can either uninstall it or leave it intact and simply install Message Queue 4.2 in a different location in your file system.
If you choose to uninstall your previous version before installing Message Queue 4.2, you may first want to back up any instance data (configuration properties, file-based persistent data store, log files, flat-file user repository, access control properties file) that you want to preserve. Instance data is not automatically migrated to the new Message Queue 4.2 location, so you must move or copy it manually from its old location in the previous installation’s IMQ_VARHOME\instances directory to that of the new installation (by default, C:\Program Files\Sun\MessageQueue\var\instances). After installing Message Queue 4.2, remove any references to uninstalled versions’ IMQ_HOME\bin directories from the system’s PATH environment variable and add the new Message Queue 4.2 installation’s IMQ_HOME\bin directory.