I am having the same problem. I have a security camera send a Jpeg to my site every 30 seconds. In the placeholder head section I have the the following code: <meta http-equiv="refresh" content="30" > This no longer works it does not change the jpeg. Pressing Ctrl+F5 works and the jpeg changes. I would like to try Acorn suggestions.

<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate">
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Expires" content="0">

Do I add all three lines or try one at a time? and how would I add The refresh every 30 seconds to the code?