Our team has been experiencing a recurring problem with velocity templates. Upon rendering, some throw a RuntimeException with the message "Template.merge() failure - Unable to render Velocity Template, '/template.vm'". We have not been able to reproduce the problem and the documentation on the web is pretty insufficient. The problem is not consistently reproducible - the same templates whose rendering sometimes causes the error also manage to display without problems at other times. The Template class source code is also of little help. Thank you in advance.
Edit: Based on Nathan Bubna's response I need to clarify that we are using Velocity version 1.4.
Edit: Since it was pointed out that a stack trace would be beneficial, here it is:
2008-09-15 11:07:57,336 ERROR velocity - Template.merge() failure. The document is null, most likely due to parsing error. 2008-09-15 11:07:57,336 ERROR VelocityResult - Unable to render Velocity Template, '/search/[template-redacted].vm' java.lang.Exception: Template.merge() failure. The document is null, most likely due to parsing error. at org.apache.velocity.Template.merge(Template.java:277) at com.opensymphony.webwork.dispatcher.VelocityResult.doExecute(VelocityResult.java:91) at com.opensymphony.webwork.dispatcher.WebWorkResultSupport.execute(WebWorkResultSupport.java:109) at com.opensymphony.xwork.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:258) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:182) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164) at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:116) at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:272) at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:237) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:39) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) at org.nanocontainer.nanowar.webwork2.PicoObjectFactoryFilter.doFilter(PicoObjectFactoryFilter.java:46) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) at org.nanocontainer.nanowar.ServletRequestContainerFilter.doFilter(ServletRequestContainerFilter.java:44) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) at com.bostoncapital.stuyvesant.RememberUserNameFilter.doFilter(RememberUserNameFilter.java:30) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:482) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:526) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:825) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:738) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:526) at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684) at java.lang.Thread.run(Unknown Source)
