In some cases, the installation is unable to proceed. In other cases, PDF Exports in the entire instance are broken. Each attempt results in the following exception being thrown:
Prior to that, the following Error appears:
At first glance, the problem looks to be a missing or incorrect class being referenced in Confluence; specifically, the prime suspect is the fop jar in the /confluence/WEB-INF/lib directory.
The issue seems to be from the missing AWT Library. Although the error message asked to check that Headless mode is enabled, this is actually already enabled by default in the*setenv.sh of standalone Confluence distributions. The conclusion here is that the problem is called by the missing X11 libraries.
A missing resources for the JDK, specifically libXp.so.6 from the deprecated X11 rpm.