When manually upgrading (manual offline and manual rolling upgrade) from version 4.x to version 6.x and switching from classic mode to YARN mode, you must manually update the Hadoop configuration file.
This task is applicable only if you are upgrading from any version of 4.x to any version of 6.x and you did not convert from classic mode to YARN mode before the upgrade. In addition, this step is applicable for only the manual offline upgrade and the manual rolling upgrade. This step is not applicable when using the Installer upgrade method.