Index: trunk/src/org/openstreetmap/josm/io/CertificateAmendment.java
===================================================================
--- trunk/src/org/openstreetmap/josm/io/CertificateAmendment.java	(revision 10075)
+++ trunk/src/org/openstreetmap/josm/io/CertificateAmendment.java	(revision 10076)
@@ -96,5 +96,5 @@
             byte[] sha = md.digest(certBytes);
             if (!SHA_HASHES[i].equals(Utils.toHexString(sha)))
-                throw new RuntimeException(tr("certificate hash mismatch"));
+                throw new RuntimeException(tr("Error adding certificate {0} - hash mismatch. Expected {1}, was {2}", CERT_AMEND[i], SHA_HASHES[i], Utils.toHexString(sha)));
 
             ByteArrayInputStream certIS = new ByteArrayInputStream(certBytes);