diff --git a/cadc-access-control/src/main/java/ca/nrc/cadc/ac/client/GMSClient.java b/cadc-access-control/src/main/java/ca/nrc/cadc/ac/client/GMSClient.java
index a13a3f123b765223a04359d410f786f1db62cfa3..bc5bd3df594630e34b86e93ef04422d8cacb1d17 100755
--- a/cadc-access-control/src/main/java/ca/nrc/cadc/ac/client/GMSClient.java
+++ b/cadc-access-control/src/main/java/ca/nrc/cadc/ac/client/GMSClient.java
@@ -1123,7 +1123,7 @@ public class GMSClient implements TransferListener
                 } 
                 if (!domainMatch)
                 {
-                    throw new AccessControlException("No valid public credentials.");
+                    throw new AccessControlException("no SSOCookieCredential for domain " + domain);
                 }
             }
             catch(IOException ex)