When adding a Post Build Action Join Trigger nothing happens. In log you find the following stacktrace
Failed to evaluate the template closure
org.apache.commons.jelly.JellyTagException: jar:file:/var/cache/jenkins/war/WEB-INF/lib/jenkins-core-2.107.1.jar!/lib/form/hetero-list.jelly:131:100: <st:include> hudson/tasks/Mailer$DescriptorImpl
at org.apache.commons.jelly.impl.TagScript.handleException(TagScript.java:745)
at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:289)
at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99)
at org.apache.commons.jelly.tags.define.InvokeBodyTag.doTag(InvokeBodyTag.java:91)
at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269)
at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95)
at org.apache.commons.jelly.TagSupport.invokeBody(TagSupport.java:161)
at org.apache.commons.jelly.tags.core.OtherwiseTag.doTag(OtherwiseTag.java:41)
at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269)
at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95)
at org.apache.commons.jelly.TagSupport.invokeBody(TagSupport.java:161)
at org.apache.commons.jelly.tags.core.ChooseTag.doTag(ChooseTag.java:38)
at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269)
at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95)
at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105)
at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120)
at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99)
at org.kohsuke.stapler.jelly.DefaultScriptInvoker.invokeScript(DefaultScriptInvoker.java:63)
at org.kohsuke.stapler.jelly.DefaultScriptInvoker.invokeScript(DefaultScriptInvoker.java:53)
at hudson.widgets.RenderOnDemandClosure$1.generateResponse(RenderOnDemandClosure.java:123)
at org.kohsuke.stapler.HttpResponseRenderer$Default.handleHttpResponse(HttpResponseRenderer.java:124)
at org.kohsuke.stapler.HttpResponseRenderer$Default.generateResponse(HttpResponseRenderer.java:69)
at org.kohsuke.stapler.Function.renderResponse(Function.java:136)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:119)
at org.kohsuke.stapler.MetaClass$JavaScriptProxyMethodDispatcher.doDispatch(MetaClass.java:473)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845)
at org.kohsuke.stapler.MetaClass$10.dispatch(MetaClass.java:374)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:782)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:649)
at org.kohsuke.stapler.Stapler.service(Stapler.java:199)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:841)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:154)
at hudson.plugins.greenballs.GreenBallFilter.doFilter(GreenBallFilter.java:59)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:157)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:99)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at jenkins.security.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:117)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at jenkins.security.BasicHeaderProcessor.doFilter(BasicHeaderProcessor.java:93)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:67)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:90)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:171)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:49)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:82)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.kohsuke.stapler.DiagnosticThreadNameFilter.doFilter(DiagnosticThreadNameFilter.java:30)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:190)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
at org.eclipse.jetty.server.Server.handle(Server.java:564)
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:317)
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110)
at org.eclipse.jetty.io.ssl.SslConnection.onFillable(SslConnection.java:278)
at org.eclipse.jetty.io.ssl.SslConnection$3.succeeded(SslConnection.java:148)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110)
at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124)
at org.eclipse.jetty.util.thread.Invocable.invokePreferred(Invocable.java:128)
at org.eclipse.jetty.util.thread.Invocable$InvocableExecutor.invoke(Invocable.java:222)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:294)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:199)
at winstone.BoundedExecutorService$1.run(BoundedExecutorService.java:77)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NoClassDefFoundError: hudson/tasks/Mailer$DescriptorImpl
at join.JoinTrigger$DescriptorImpl.getApplicableDescriptors(JoinTrigger.java:393)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.commons.jexl.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:258)
at org.apache.commons.jexl.parser.ASTMethod.execute(ASTMethod.java:104)
at org.apache.commons.jexl.parser.ASTReference.execute(ASTReference.java:83)
at org.apache.commons.jexl.parser.ASTReference.value(ASTReference.java:57)
at org.apache.commons.jexl.parser.ASTGTNode.value(ASTGTNode.java:62)
at org.apache.commons.jexl.parser.ASTExpression.value(ASTExpression.java:54)
at org.apache.commons.jexl.parser.ASTExpressionExpression.value(ASTExpressionExpression.java:56)
at org.apache.commons.jexl.ExpressionImpl.evaluate(ExpressionImpl.java:80)
at hudson.ExpressionFactory2$JexlExpression.evaluate(ExpressionFactory2.java:74)
at org.apache.commons.jelly.expression.ExpressionSupport.evaluateRecurse(ExpressionSupport.java:61)
at org.apache.commons.jelly.expression.ExpressionSupport.evaluateAsBoolean(ExpressionSupport.java:71)
at org.apache.commons.jelly.tags.core.CoreTagLibrary$1.run(CoreTagLibrary.java:97)
at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95)
at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105)
at org.kohsuke.stapler.jelly.JellyViewScript.run(JellyViewScript.java:95)
at org.kohsuke.stapler.jelly.IncludeTag.doTag(IncludeTag.java:147)
at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269)
... 100 more
Caused by: java.lang.ClassNotFoundException: hudson.tasks.Mailer$DescriptorImpl
at jenkins.util.AntClassLoader.findClassInComponents(AntClassLoader.java:1374)
at jenkins.util.AntClassLoader.findClass(AntClassLoader.java:1327)
at jenkins.util.AntClassLoader.loadClass(AntClassLoader.java:1080)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 122 more
Caused by: java.lang.NoClassDefFoundError: hudson/tasks/Mailer$DescriptorImpl
at join.JoinTrigger$DescriptorImpl.getApplicableDescriptors(JoinTrigger.java:393)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
Make sure that the plugin is installed. Likely JoinTrigger has issues with optional dependencies which are not actually optional