Proxy Error with ColdFusion 8, but not with Railo3.1! Whats going on?

I have installed Apache 2.2.11, jboss 5.1.0.GA, ColdFusion 8.0.1 and Railo 3.1.0.015.

Railo and ColdFusion are served through jboss as exploded WAR and EAR and both are available as VirtualHosts on port 80 through Apache, the details are available here (thank you Indiver Nagpal): http://nagpals.com/blog/post.cfm/running-railo-and-adobe-coldfusion-on-the-same-context-root-in-jboss

I am developing a small project but have now encountered a problem with Apache and/or ColdFusion.

When i navigate to my site http://cf8.local/myproject/user-update.cfm and fill out a form, which on submit triggers a database update and returns to the same site, i get the following error:

502 Proxy Error
Proxy Error
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request POST /myproject/user-update.cfm.
Reason: Error reading from remote server

When i open the same site through railo (http://railo.local/myproject/update-user.cfm) everything works as expected (i expect an error debug-output).

What can cause this behaviour? Is it a ColdFusion misconfiguration or an Apache misconfiguration?

From serverfault mrt181

• Is the ColdFusion code executing properly? I would check the ColdFusion error logs to ensure that ColdFusion isn't experiencing an exception or runtime error that the proxy isn't able to return properly.

  mrt181 : i made a change in my code to make my program run. i have forgot to write that railo has shown an error output (as expected) while ColdFusion has greeted me with the mentioned Apache Error. Everything works now.
  From Justin Scott