The cache-control and pragma HTTP header have not been set properly or are missing allowing the browser and proxies to cache content. aspnet code example

Example 1: do not chache pages

<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">

Example 2: Cache-Control: no-cache, no-store Expires: 0 Pragma: no-cache

header("Cache-Control: no-cache, no-store, must-revalidate"); // HTTP 1.1.
header("Pragma: no-cache"); // HTTP 1.0.
header("Expires: 0"); // Proxies.