Merge branch 'MDL-48873_master' of https://github.com/StudiUM/moodle

auth/cas/auth.php

@@ -113,6 +113,12 @@ class auth_plugin_cas extends auth_plugin_ldap {
 
         // If the multi-authentication setting is used, check for the param before connecting to CAS.
         if ($this->config->multiauth) {
+
+            // If there is an authentication error, stay on the default authentication page.
+            if (!empty($SESSION->loginerrormsg)) {
+                return;
+            }
+
             $authCAS = optional_param('authCAS', '', PARAM_RAW);
             if ($authCAS == 'NOCAS') {
                 return;