3. Register and Install Target Version
This section describes the steps to register the software repositories with Ambari for the new target version (i.e. the version you will be upgrading to) and how to install the software on all host prior to performing the upgrade.
![[Important]](../common/images/admon/important.png) | Important |
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If you are running HDP 2.1, once you register a version for HDP 2.3 (and not installing or upgrading yet to HDP 2.3), when attempting to add a service, Ambari will use the new HDP 2.3 bits instead of the expected HDP 2.1 bits. Therefore, only register an HDP 2.3 repo immediately before you are ready to start Express Upgrade from HDP 2.1 to 2.3. |