Attempts to install IBM Rational License Key Server on UNIX and Linux results in the error "Unexpected error occurred".
Rational License Key Server 8.1.3 requires minimum IBM Installation Manager version 1.5.2.
Installing the installation manager will attempt to upgrade automatically from any previous version to 1.5.2 which results in the above mentioned error.
Resolving the problem
Download and install/update to latest version of IBM Installation Manager on the machine where Rational License Key Server is planned to be installed.
After Installation Manager is updated to the latest version, attempt to install Rational License Key Server again.