Getting php error on production but not development

[eluser]CroNiX[/eluser]
CI's output is buffered when using views, etc. When you echo directly from a controller, that output gets sent immediately followed by the contents of the buffer.

It's best to send any output to the buffer instead of echoing it directly.

Code:

$output = "R ";
$output .= printf("%.2f", "$deliveryTotal");
$output .= '<input type="hidden" name="total" value="' . $total  . '" id="totalval" />';

$this->output->set_output($output);

Your session is sending output to the browser (probably a cookie, sent with a header), so that's where the buffering is coming into play.