diff --git a/admin/index.php b/admin/index.php
index 3953f24e488..496b709a09f 100644
--- a/admin/index.php
+++ b/admin/index.php
@@ -224,6 +224,7 @@
         $origdebug = $CFG->debug;
         $CFG->debug = DEBUG_MINIMAL;
         error_reporting($CFG->debug);
+        $CFG->xmlstrictheaders = false;
 
         // logo ut in case we are upgrading from pre 1.9 version in order to prevent
         // weird session/role problems caused by incorrect data in USER and SESSION
@@ -333,7 +334,7 @@
 
                 // Update core message providers
                 message_update_providers();
-		message_update_providers('message');
+                message_update_providers('message');
 
                 if (set_config("version", $version)) {
                     remove_dir($CFG->dataroot . '/cache', true); // flush cache
@@ -367,6 +368,10 @@
         }
     }
 
+    // Turn off xmlstrictheaders during upgrade.
+    $origxmlstrictheaders = !empty($CFG->xmlstrictheaders);
+    $CFG->xmlstrictheaders = false;
+
 /// Find and check all main modules and load them up or upgrade them if necessary
 /// first old *.php update and then the new upgrade.php script
     upgrade_activity_modules("$CFG->wwwroot/$CFG->admin/index.php");  // Return here afterwards
@@ -436,6 +441,9 @@
 
     unset($SESSION->installautopilot);
 
+    // Turn xmlstrictheaders back on now.
+    $CFG->xmlstrictheaders = $origxmlstrictheaders;
+
 /// Set up the blank site - to be customized later at the end of install.
     if (! $site = get_site()) {
         // We are about to create the site "course"