Failed appending the header value with 413 response in Apache HTTPD using mod_jk

Issue

• We use mod_jk, and see a 413 response for some requests:

  Request Entity Too Large
  The requested resource
  /app does not allow request data with GET requests, or the amount of data provided in the request exceeds the capacity limit.  
  

• And mod_jk logs show:

  [error] ajp_marshal_into_msgb::jk_ajp_common.c (476): (node1) failed appending the header value for header 'Authorization' of length 13
  [info] ajp_service::jk_ajp_common.c (2577): (node1) Creating AJP message failed without recovery - check max_packet_size
  

• Wireshark trace shows that web server is rejecting with the response below, but the same error is not present either in JBoss EAP logs or in the apache logs in debug mode.

  Hypertext Transfer Protocol
      HTTP/1.1 413 Request Entity Too Large\r\n
          [Expert Info (Chat/Sequence): HTTP/1.1 413 Request Entity Too Large\r\n]
              [Message: HTTP/1.1 413 Request Entity Too Large\r\n]
              [Severity level: Chat]
              [Group: Sequence]
          Request Version: HTTP/1.1
          Status Code: 413
          Response Phrase: Request Entity Too Large
      Date: Fri, 15 Feb 2013 21:49:36 GMT\r\n
      Server: Apache/2.2.15 (Red Hat)\r\n
      Connection: close\r\n
      Content-Type: text/html; charset=iso-8859-1\r\n
      \r\n
  
  [ajp-10.10.10.10-8009-1] DEBUG (org.jboss.ws.core.soap.MessageFactoryImpl) - createMessage: [contentType=multipart/related; 
  boundary=MIMEBoundary_31c97d726c91ad383489007f7b814a12eee5a08a363091bf; 
  type="application/xop+xml"; 
  start="<0.21c97d726c91ad383489007f7b814a12eee5a08a363091bf@apache.org>"; 
  start-info="application/soap+xml"; action="urn:processNPCMsg"]
  
  [ajp-10.10.10.10-8009-1] DEBUG (org.apache.coyote.ajp.AjpMessage) - Received 0 18
  [ajp-10.10.10.10-8009-1] TRACE (org.jboss.ws.core.soap.MessageFactoryImpl) - createMessage
  
  [ajp-10.10.10.10-8009-1] DEBUG (org.jboss.ws.metadata.umdm.EndpointMetaData) - Configure SOAPBinding
  [ajp-10.10.10.10-8009-1] ERROR (org.jboss.ws.core.jaxws.SOAPFaultHelperJAXWS) - SOAP request exception
  java.lang.IllegalArgumentException: multipart/related stream invalid, no root part was found
      at org.jboss.ws.core.soap.attachment.MultipartRelatedDecoder.decodeMultipartRelatedMessage(MultipartRelatedDecoder.java:171)
  

• How to increase the maxPostSize value from default 2MB to 10MB to upload larger files?