I solved the problem. There are 2 possible answers: 1. Change DataSource pool size parameter (second argument) of dataSourceObjectPoolFactory bean constructor in /jasperserver/WEB-INF/applicationContext.xml file (default is 5): Reload application after saving changes. 2. Use JNDI source instead of JDBC source and set JNDI connection following JasperReports Server Admin Guide or Appache Tomcat documentation: http://tomcat.apache.org/tomcat-6.0-doc/jndi-datasource-examples-howto.html