To upgrade from version 5 of Zend Server for IBM i to version 6 or higher, it is necessary to migrate to the newer version. This is because version 5 was created as a different Licensed Program than the newer versions.
Any point version of Zend Server 5 for IBM i needing to be upgraded to version 6 or higher, running on any supported version of IBM i.
While the current version is no longer 6, The directory and library names for version 9 are zendphp7 and ZENDPHP7, and the ports are 10090 and 10091, but the rest of the directions should be mostly applicable after making those substitutions.
The first step in the migration is simply to download and install the latest available version of Zend Server. This can be done while Zend Server 5 is running, and both Zend Server 5 and the latest version can run side by side, on the same partition, at the same time. Here are some notes that can get you started with the installation of the latest version:
Download and install Zend Server for IBM i, versions 2019 and earlier