diff --git a/mod/assign/upgradelib.php b/mod/assign/upgradelib.php
index c34276e70fd..e1e63b9dadd 100644
--- a/mod/assign/upgradelib.php
+++ b/mod/assign/upgradelib.php
@@ -56,11 +56,6 @@ class assign_upgrade_manager {
         global $DB, $CFG, $USER;
         // Steps to upgrade an assignment.
 
-        // Is the user the admin? admin check goes here.
-        if (!is_siteadmin($USER->id)) {
-              return false;
-        }
-
         core_php_time_limit::raise(ASSIGN_MAX_UPGRADE_TIME_SECS);
 
         // Get the module details.
@@ -71,6 +66,14 @@ class assign_upgrade_manager {
                                            '*',
                                            MUST_EXIST);
         $oldcontext = context_module::instance($oldcoursemodule->id);
+        // We used to check for admin capability, but since Moodle 2.7 this is called
+        // during restore of a mod_assignment module.
+        // Also note that we do not check for any mod_assignment capabilities, because they can
+        // be removed so that users don't add new instances of the broken old thing.
+        if (!has_capability('mod/assign:addinstance', $oldcontext)) {
+            $log = get_string('couldnotcreatenewassignmentinstance', 'mod_assign');
+            return false;
+        }
 
         // First insert an assign instance to get the id.
         $oldassignment = $DB->get_record('assignment', array('id'=>$oldassignmentid), '*', MUST_EXIST);