title: SRVE8094W: WARNING: Cannot set header. Response already committed - upgrading GWT/Spring application to WAS 8.5
body: <p>I'm upgrading app server of somewhat old GWT 2.03/Spring 2 application from WAS 7.00 to WAS 8.5.5 and I'm getting the following error when I try to load that very first Login JSP:</p>
  
  <pre><code>[5/11/15 15:55:18:969 EDT] 0000010e ServletWrappe I com.ibm.ws.webcontainer.servlet.ServletWrapper init SRVE0242I: [RxHD_Ear] [/RxHD] [/rxhd_login.jsp]: Initialization successful.
  [5/11/15 15:55:20:000 EDT] 0000010f SRTServletRes W com.ibm.ws.webcontainer.srt.SRTServletResponse setHeader SRVE8094W: WARNING: Cannot set header. Response already committed.
  [5/11/15 15:55:20:005 EDT] 0000010e SRTServletRes W com.ibm.ws.webcontainer.srt.SRTServletResponse setHeader SRVE8094W: WARNING: Cannot set header. Response already committed.
  </code></pre>
  
  <p>The JSP that get's loaded doesn't contain any logic. It only renders some HTML content using couple of CSS classes.</p>
  
  <p>This application runs fine on WAS 7 and we never had any problems upgrading from WAS 6 to WAS 7. I compared all settings in WAS 8.5.5 and WAS 7 and don't see any differences including the build path and Class Loader settings. 
  Also, there are no other error messages or Stack trace anywhere in the logs. I also tried running the server with different versions of JVM and different modes of Class Loader like <code>PARENT_FIST</code> and <code>PARENT_LAST</code>.</p>
  
  <p>Nothing seems to work so far.</p>
  
  <p>I ran a trace on both versions of the WAS server and went over all logged messages. Even though there are some different messages being logged, I don't see anything alarming so far (output buffer size, output stream being committed). I can provide both trace files if needed.</p>
  
  <p>Does anybody have any idea or experienced something similar by any chance?</p>
  
  <p>Thanks in advance.</p>
  
  <p>Paul.</p>