An unknown error has occurred. No chart found.

2015-12-10 09:47:46,740 ERROR [http-bio-80-exec-13] [runtime] get(chart) failed on instance of com.atlassian.bamboo.webwork.StarterAction
get(chart) failed on instance of com.atlassian.bamboo.webwork.StarterAction
The problematic instruction:
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==> if action.chart?has_content [on line 1, column 1 in URLTemplate]
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Java backtrace for programmers:
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freemarker.template.TemplateModelException: get(chart) failed on instance of com.atlassian.bamboo.webwork.StarterAction
	at freemarker.ext.beans.BeanModel.get(BeanModel.java:210)
	at freemarker.core.Dot._getAsTemplateModel(Dot.java:76)
	at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
	at freemarker.core.BuiltIn$has_contentBI._getAsTemplateModel(BuiltIn.java:666)
	at freemarker.core.BuiltIn$has_contentBI.isTrue(BuiltIn.java:678)
	at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:77)
	at freemarker.core.Environment.visit(Environment.java:210)
	at freemarker.core.Environment.process(Environment.java:190)
	at freemarker.template.Template.process(Template.java:289)
	at freemarker.template.Template.process(Template.java:243)
	at com.atlassian.bamboo.ww2.BambooFreemarkerManager.renderText(BambooFreemarkerManager.java:554)
...
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at freemarker.ext.beans.BeansWrapper.invokeMethod(BeansWrapper.java:805)
	at freemarker.ext.beans.BeanModel.invokeThroughDescriptor(BeanModel.java:251)
	at freemarker.ext.beans.BeanModel.get(BeanModel.java:176)
	... 273 more
Caused by: java.lang.NullPointerException
	at sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1264)
	at sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:219)
	at sun.awt.FontConfiguration.init(FontConfiguration.java:107)
	at sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:776)
	at sun.font.SunFontManager$2.run(SunFontManager.java:431)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.font.SunFontManager.<init>(SunFontManager.java:376)
	at sun.awt.X11FontManager.<init>(X11FontManager.java:57)
	... 280 more

Caused by: java.lang.NoClassDefFoundError: org.jfree.chart.JFreeChart (initialization failure)
    at java.lang.J9VMInternals.initializationAlreadyFailed(J9VMInternals.java:121)
    at org.jfree.chart.ChartFactory.createXYBarChart(ChartFactory.java:1517)
    at com.atlassian.bamboo.charts.author.AuthorNumberBuildsBarChart.getJFreeChart(AuthorNumberBuildsBarChart.java:73)
    at com.atlassian.bamboo.charts.author.AuthorNumberBuildsBarChart.generateChartParams(AuthorNumberBuildsBarChart.java:41)
    at com.atlassian.bamboo.webwork.StarterAction.getChart(StarterAction.java:489)
    ... 275 more
Caused by: java.lang.InternalError: Can't connect to X11 window server using 'localhost:10.0' as the value of the DISPLAY variable.
    at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)
    at sun.awt.X11GraphicsEnvironment.access$200(X11GraphicsEnvironment.java:77)
    at sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:122)
    at java.security.AccessController.doPrivileged(AccessController.java:274)
    at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:86)