After updating the system, consider the following changes:
If the system is a SPARC system and uses fiber channel storage, see SPARC: Configuration Changes for Fiber Channel Storage.
If the java command is not found, see Using Java 8.
$ java -bash: java: command not found
If MySQL 5.1 is installed, see How to Update to MySQL 5.5 After Updating Your System To Oracle Solaris 11.4.
On any system that is running an OpenLDAP server, remove the old OpenLDAP database and import the new LDIF data as described in How to Migrate Existing OpenLDAP Server Configuration in Working With Oracle Solaris 11.4 Directory and Naming Services: LDAP.
Consider the effects of version updates of bundled software. See Oracle Solaris 11.4 Bundled Software Updates in Freeware Available in Oracle Solaris 11.4. Check the documentation that is maintained by the third-party vendor or FOSS community for particular software components for any issues related to updating the version of that software as part of the Oracle Solaris update.
In particular for this release, if you have Puppet installed, see What’s New in Puppet in Oracle Solaris 11.4 in Using Puppet to Perform Configuration Management in Oracle Solaris 11.4.