Index: formsets.py
===================================================================
--- formsets.py	(revision 12657)
+++ formsets.py	(working copy)
@@ -54,7 +54,7 @@
         if self.data or self.files:
             form = ManagementForm(self.data, auto_id=self.auto_id, prefix=self.prefix)
             if not form.is_valid():
-                raise ValidationError('ManagementForm data is missing or has been tampered with')
+                raise ValidationError('ManagementForm data is missing or has been tampered with  %s' % self._errors)
         else:
             form = ManagementForm(auto_id=self.auto_id, prefix=self.prefix, initial={
                 TOTAL_FORM_COUNT: self.total_form_count(),