I'm sorry for the delay, but I've been on holidays. The page that is returned is a very simple HTML response. It only says "Internal Server Error". The title of the page is "Error". It outputs that content only. Nothing else.

Checking the error today, I've discovered that it only happens when I throw a specific type of exception. It's the java.io.IOException. If I throw this one or other class that inherits from it, such as java.net.SocketException, the exception seems to be "swallowed" by the server, in production mode.

To test it, you only need to write the following JSP file:

   if (true) {

      throw new java.io.IOException ("");

   }

I'm going to wait for your answer before opening a JIRA, just in case that it's the right behaviour of Wildfly.

Thank you for your help!

Hello Jaikiran:

In the simplest test that I've done, I've not used a "web.xml" file at all. I've created a simple WAR (as a directory), without deployment descriptor, and with a single JSP inside. But it hasn't logged the exception either. Even in a clean install of Wildfly. You can try to reproduce it yourself following these steps:

  unzip wildfly-8.1.0.Final.zip

  cd wildfly-8.1.0.Final/standalone/deployments/

  mkdir -p test.war/WEB-INF/

  vim test.war/index.jsp

  (Write a JSP that throws an IOException)

  ../../bin/standalone.sh

Then, in the browser, enter "http://localhost:8080/test". The page output shows the stack trace, but it isn't written neither in the console nor the log file :/ . However, if you enable the JSP development mode, it's.

PS: By the way, I forgot to clarify one thing. The page that simply returned the message "Internal Server Error" was accessed in a non-local IP. That's why it didn't show the stack trace. I've accessed it in the IP 127.0.0.1 just now, and it effectively prints the stack trace. So it has no relation with the error that I've been commenting.

Hello:

Thank you for clarifying this issue . I've opened a ticket here, in the Undertow JIRA: https://issues.jboss.org/browse/UNDERTOW-296 . I hope to have done it correctly.

Stuart Douglas has responded to my JIRA ticket. He has said that it's intentional, to prevent DoS attacks. It seems that it's easy for an attacker to cause IOExceptions, so these are silenced in production mode. However one can enable its logging by setting the log category "io.undertow.request.io" to level DEBUG.

Thank you for the help!