rename(assets/uploads/AC925972.pdf ,assets/uploads/ABcd.pdf): The filename, directory name, or volume label syntax is incorrect. (code: 123)

Question

I write following code in codeigniter controller in which following error show:

rename(assets/uploads/AC925972.pdf ,assets/uploads/ABcd.pdf): The filename, directory name, or volume label syntax is incorrect. (code: 123)

$path=AC545.pdf;
$old = "assets/uploads/$path";
$new = "assets/uploads/ABcd.pdf";
rename($old, $new);

Answer 1

Change

$path=AC545.pdf;

to

$path="AC545.pdf";