You will get this error only when you try to redirect a page after you already have flushed the output
buffer. This happens because HTTP specification force the header to be set up before the lay out of the
page can be shown. When you try to send a redirect status, your HTTP server cannot send it right now if
it hasn’t finished to set up the header. Simply it is giving the error due to the specification of HTTP
1.0 and 1.1 .