Index: openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl,v
diff -u -r1.118.2.29 -r1.118.2.30
--- openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl	31 Aug 2016 10:55:14 -0000	1.118.2.29
+++ openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl	5 Sep 2016 08:53:23 -0000	1.118.2.30
@@ -605,6 +605,14 @@
         return filter_return
     }
 
+    if {[ns_set get [ns_conn headers] Upgrade-Insecure-Requests 0]
+        && [security::https_available_p]
+        && ![security::secure_conn_p]
+    } {
+        security::redirect_to_secure -script_abort=false [ad_return_url -qualified]
+        return filter_return
+    }
+
     # 2. handle special case: if the root is a prefix of the URL, 
     #                         remove this prefix from the URL, and redirect.
     if { $root ne "" } {