As Dashboard Report Plugin generates graphics with JFreeChart, a graphic environnement must exist.
This is a Java (AWT/Java2D) issue, not something that is specific to JFreeChart. see JFreeChart FAQ .
To take advantage of graphics or Historic report, you must install a minimum XWindow server on your unix machine.
If it is not possible ,
<project>
[...]
<build>
[...]
<plugins>
[...]
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>dashboard-maven-plugin</artifactId>
<version>1.0-SNAPSHOT</version>
<!-- common configurations -->
<configuration>
<!-- disable the graphics generation -->
<generateGraphs>
false
<generateGraphs>
[...]
</configuration>
</plugin>
[...]
</plugins>
[...]
</build>
[...]
</project>