--- a/taskcluster/taskgraph/transforms/base.py
+++ b/taskcluster/taskgraph/transforms/base.py
@@ -1,15 +1,16 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 from __future__ import absolute_import, print_function, unicode_literals
 
 import re
+import pprint
 import voluptuous
 
 
 class TransformConfig(object):
     """A container for configuration affecting transforms.  The `config`
     argument to transforms is an instance of this class, possibly with
     additional kind-specific attributes beyond those set here."""
     def __init__(self, kind, path, config, params):
@@ -64,17 +65,17 @@ def validate_schema(schema, obj, msg_pre
     beginning with msg_prefix.
     """
     try:
         return schema(obj)
     except voluptuous.MultipleInvalid as exc:
         msg = [msg_prefix]
         for error in exc.errors:
             msg.append(str(error))
-        raise Exception('\n'.join(msg))
+        raise Exception('\n'.join(msg) + '\n' + pprint.pformat(obj))
 
 
 def get_keyed_by(item, field, item_name, subfield=None):
     """
     For values which can either accept a literal value, or be keyed by some
     other attribute of the item, perform that lookup.  For example, this supports
 
         chunks: