Caused by: java.lang.IllegalStateException: Cannot obtain Writer because OutputStream is already in use - liferay-6

Question

I am getting the below error when trying to download file in liferay
05:03:35,867 ERROR [[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'][PortletRequestDispatcherImpl:115] org.springframework.web.util.NestedServletException: View rendering failed; nested exception is java.lang.IllegalStateException: Cannot obtain Writer because OutputStream is already in use
org.springframework.web.util.NestedServletException: View rendering failed; nested exception is java.lang.IllegalStateException: Cannot obtain Writer because OutputStream is already in use
at org.springframework.web.servlet.ViewRendererServlet.processRequest(ViewRendererServlet.java:96)
at org.springframework.web.servlet.ViewRendererServlet.doGet(ViewRendererServlet.java:67)
Caused by: java.lang.IllegalStateException: Cannot obtain Writer because OutputStream is already in use
at com.liferay.portlet.MimeResponseImpl.getWriter(MimeResponseImpl.java:90)
at com.liferay.portlet.PortletServletResponse.getWriter(PortletServletResponse.java:207)
at com.netcracker.portal.framework.spring.templates.view.SoyDataView.renderMergedOutputModel(SoyDataView.java:93)
and below is the code, i tried searching online but none of them have worked
String defaultFileName = "hello.pdf";
resourceResponse.setContentType("application/octet-stream");
resourceResponse.addProperty(GenericServiceTransport.CONTENT_DISPOSITION, "attachment; filename= hello.pdf" );
resourceResponse.flushBuffer();
try {
out = resourceResponse.getPortletOutputStream();
out.write(backendFile.getContent());
out.flush();
out.close();
} catch (IOException e) {
logger.error(e.getMessage());
}
return;

Answer 1

As first item I'd try to remove the flushBuffer call. You probably get the exception in the line following it, and flushing the buffer surely will use the output stream.
If that doesn't help, please add mute code, e.g. the complete method including its signature