Running a simple report on a Linux system yields:
Alert The server has encountered an error. Please excuse the inconvenience. Error Message net.sf.jasperreports.engine.util.JRFontNotFoundException: Font 'Arial' is not available to the JVM. See the Javadoc for more details.
The following setting in jasperreports.properties does not have any effect. net.sf.jasperreports.awt.ignore.missing.font=true
The following link describes how to add a font to iReport and then export it as a font extension: iReport - Fonts.
Taking the exported font extension and adding it to the classpath of JasperServer should resolve the missing font issue. You can do this by simply adding it to the WEB_INF/lib directory and restarting the server.
Ref. Case #00023243 -- 00:55, 22 December 2011 (UTC)