Error

VelocityViewServlet : Error processing the template

Invocation of method 'getSession' in  class org.apache.catalina.connector.RequestFacade threw exception java.lang.IllegalStateException: Cannot create a session after the response has been committed @ /WEB-INF/templates/template/header.vm[44,23]
org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getSession' in class org.apache.catalina.connector.RequestFacade threw exception java.lang.IllegalStateException: Cannot create a session after the response has been committed @ /WEB-INF/templates/template/header.vm[44,23] at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:286) at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203) at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:419) at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:73) at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:125) at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318) at org.apache.velocity.runtime.directive.Parse.render(Parse.java:224) at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170) at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318) at org.apache.velocity.Template.merge(Template.java:254) at org.apache.velocity.tools.view.servlet.VelocityViewServlet.mergeTemplate(VelocityViewServlet.java:619) at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doRequest(VelocityViewServlet.java:434) at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doGet(VelocityViewServlet.java:392) at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at tenders.filter.SuspiciousUrlFilter.doFilter(SuspiciousUrlFilter.java:54) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at tenders.filter.IntecCsrfPreventionFilter.doFilter(IntecCsrfPreventionFilter.java:320) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:687) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:359) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:889) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1735) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748) Caused by: java.lang.IllegalStateException: Cannot create a session after the response has been committed at org.apache.catalina.connector.Request.doGetSession(Request.java:3060) at org.apache.catalina.connector.Request.getSession(Request.java:2492) at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:908) at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:920) at sun.reflect.GeneratedMethodAccessor272.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295) at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245) ... 42 more