we are having problems getting our taskException emails to render after upgrade

javax.resource.spi.work.WorkCompletedException: com.appiancorp.process.engine.EmailBodyException: Email body failed to render
          at org.jboss.jca.core.workmanager.WorkWrapper.run(WorkWrapper.java:224)
          at org.jboss.threads.SimpleDirectExecutor.execute(SimpleDirectExecutor.java:33)
          at org.jboss.threads.QueueExecutor.runTask(QueueExecutor.java:808)
          at org.jboss.threads.QueueExecutor.access$100(QueueExecutor.java:45)
          at org.jboss.threads.QueueExecutor$Worker.run(QueueExecutor.java:849)
          at java.lang.Thread.run(Thread.java:745)
          at org.jboss.threads.JBossThread.run(JBossThread.java:122)
Caused by: javax.ejb.EJBException: com.appiancorp.process.engine.EmailBodyException: Email body failed to render
          at org.jboss.as.ejb3.tx.BMTInterceptor.handleException(BMTInterceptor.java:78)
          at org.jboss.as.ejb3.tx.EjbBMTInterceptor.checkStatelessDone(EjbBMTInterceptor.java:92)
          at org.jboss.as.ejb3.tx.EjbBMTInterceptor.handleInvocation(EjbBMTInterceptor.java:107)
          at org.jboss.as.ejb3.tx.BMTInterceptor.processInvocation(BMTInterceptor.java:56)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.invocation.InitialInterceptor.processInvocation(InitialInterceptor.java:21)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
          at org.jboss.as.ee.component.interceptors.ComponentDispatcherInterceptor.processInvocation(ComponentDispatcherInterceptor.java:53)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ejb3.component.pool.PooledInstanceInterceptor.processInvocation(PooledInstanceInterceptor.java:51)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ejb3.component.interceptors.CurrentInvocationContextInterceptor.processInvocation(CurrentInvocationContextInterceptor.java:41)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ejb3.component.invocationmetrics.WaitTimeInterceptor.processInvocation(WaitTimeInterceptor.java:43)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ejb3.component.interceptors.ShutDownInterceptorFactory$1.processInvocation(ShutDownInterceptorFactory.java:64)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ejb3.component.interceptors.LoggingInterceptor.processInvocation(LoggingInterceptor.java:59)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ee.component.NamespaceContextInterceptor.processInvocation(NamespaceContextInterceptor.java:50)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ejb3.component.interceptors.AdditionalSetupInterceptor.processInvocation(AdditionalSetupInterceptor.java:55)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ejb3.component.messagedriven.MessageDrivenComponentDescription$5$1.processInvocation(MessageDrivenComponentDescription.java:203)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.as.ee.component.TCCLInterceptor.processInvocation(TCCLInterceptor.java:45)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
          at org.jboss.as.ee.component.ViewService$View.invoke(ViewService.java:185)
          at org.jboss.as.ee.component.ViewDescription$1.processInvocation(ViewDescription.java:182)
          at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
          at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
          at org.jboss.as.ee.component.ProxyInvocationHandler.invoke(ProxyInvocationHandler.java:73)
          at com.appiancorp.ra.workpoller.UnattendedRequestListener$$$vi

And this forum talks about this error as connection timeout error?

stackoverflow.com/.../caused-by-java-net-socketexception-unexpected-end-of-file-from-server

Not sure why?

This error means that when trying to connect to myserver.mycompany.com:21007 to retrieve the JSP to render the email body the server myserver.mycompany.com:21007 closed the connection.

Maybe your myserver.mycompany.com:21007 server is not supposed to accept requests of type myserver.mycompany.com:21007

the actual App Server URL is myserver.mycompany.com:21007

But when I use this URL along with conf.mailhandler.mail.transport.protocol=smtps, I get the following error Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No name matching kc6barbpmapp10v.uskcmtb.amrs.bankofamerica.com found

Should we update Session Timeouts in custom.properties file and web.xml file of appian?

-          Session timeout warning in custom.properties file (current settings from prod):
resources.appian.ap.application.appian.ap.session.timeoutwarn=15
-          Session timeout in appian web.xml file (current settings from prod):
<session-config>
<!--
The timeout should be at least 5 minutes more than the value given to
resources.appian.ap.application.appian.ap.session.timeoutwarn
in custom.properties.
-->
<session-timeout>15</session-timeout>
</session-config>

No, it's not session timeout related.

What would be the port for HTTP calls in the APP_SERVER instead of HTTPS?

should be 21007

I thought you said 21007 is for HTTPS (SSL) not HTTP