Verify that any custom applications referencing /usr/hdp/current... are updated with new version. This might be found the pom.xml and could require that you recompile if there are changes.

Check your paths, which will change if you upgrade from versions before HDP 2.2.

Ensure that all libraries are referenced using /usr/hdp/current/…, to ensure that your script maintains its integrity for future upgrades.

Build processes, such as maven with declare library versions for the application in a pom.xml file must be adjusted, recompiled, and deployed during the upgrade cycle to ensure version parity with the cluster.