Same error for me. I'm trying to migrate from JR 3.1.2 to 3.5.1 15:59:32,654 ERROR [sTDERR] net.sf.jasperreports.engine.JRRuntimeException: Unknown hyperlink target 0 15:59:32,654 ERROR [sTDERR] at net.sf.jasperreports.engine.JRHyperlinkHelper.getLinkTarget(JRHyperlinkHelper.java:273) 15:59:32,654 ERROR [sTDERR] at net.sf.jasperreports.engine.base.JRBaseTextField.normalizeLinkTarget(JRBaseTextField.java:317) 15:59:32,654 ERROR [sTDERR] at net.sf.jasperreports.engine.base.JRBaseTextField.readObject(JRBaseTextField.java:381)