As I heard it more than once in the last months, it is the right time to write a blog post about it. I still don't know, why it happens so often at the moment (except of a lack of reading the documentation), but I know, how it will (hopefully) work for you, if you run in this problem (without reading the documentation).
The typical environment where this happen is a Red Hat Linux (mostly 8.x and 9.x), but it can happen on any Linux distribution.
The customers of mine all tried to install a 19c 64-bit Client on a Red Hat Linux system as the installer stopped somewhere with this message:
Preparing to launch Oracle Universal Installer from /tmp/OraInstall20XX-XX-XX_XX-XX-XXPM. Please wait ... The java.library.path system variable is missing or invalid. Please set java.library.path with a correct value and retry the operation.
Exception in thread "main" java.lang.NoClassDefFoundError: Could not initialize class oracle.sysman.oii.oiip.oiipg.OiipgPropertyLoader
First to check is always, if the java environment is set up/available correctly, but typically, it is. Second is to check the documentation for the operating systems requirements of the product you want to install - in case of 19c clients on Linux, the documentation can be found here.
In the above case, the error message "The java.library.path system variable is missing or invalid" is just wrong. Java is fine and available and the java.library.path is correct.
In this case and with the documentation you can then check the supported (kernel) version and afterwards the Linux system for the required packages, this is e.g. the list for Red Hat Linux 8.x:
bc, binutils, elfutils-libelf, elfutils-libelf-devel, fontconfig-devel, glibc, glibc-devel, ksh, libaio, libaio-devel, libXrender, libX11, libXau, libXi, libXtst, libgcc, libnsl, librdmacm, libstdc++, libstdc++-devel, libxcb, libibverbs, make, policycoreutils, policycoreutils-python-utils, smartmontools, sysstat.
There is also a section in the documentation which allows to check the optional packages required for some products, e.g. ipmiutil (for Intelligent Platform Management Interface), libnsl2 (for Oracle Database Client only), libnsl2-devel (for Oracle Database Client only), net-tools (for Oracle RAC and Oracle Clusterware), nfs-utils (for Oracle ACFS).
Now, what happend to all the customers with the above error message while installing the client? As we found out step by step, one of the required packages were not installed as X86 64bit version: The libnsl. But this isn't told by the installer - it complains about the java.library.path system variable.
All customers just installed libnsl.x86_64 as newest version using
yum install libnsl.x86_64
and then they retried the installation of the client succesfully. All other packages, except libnsl, were setup with the Red Hat installation, only libnsl was missing.
If you run an Oracle Enterprise Linux you can use the preinstall-rpm for the database (oracle-database-preinstall-19c) - by the way even if you only want to install the client - to get all the libs installed automatically. If you are on Red Hat, you really should check the libraries according to the documentation.
Yes, it is a (mostly) stupid work to compare libs, but if it prevents from a whole day searching for an error with a misleading error message...
