diff --git a/keystone/exception.py b/keystone/exception.py
index 39bf5d0fa5..d3eae889fd 100644
--- a/keystone/exception.py
+++ b/keystone/exception.py
@@ -284,11 +284,6 @@ class ForbiddenAction(Forbidden):
                        " requested action: %(action)s")
 
 
-class ImmutableAttributeError(Forbidden):
-    message_format = _("Could not change immutable attribute(s) "
-                       "'%(attributes)s' in target %(target)s")
-
-
 class CrossBackendNotAllowed(Forbidden):
     message_format = _("Group membership across backend boundaries is not "
                        "allowed, group in question is %(group_id)s, "
@@ -316,14 +311,6 @@ class EndpointNotFound(NotFound):
     message_format = _("Could not find endpoint: %(endpoint_id)s")
 
 
-class MetadataNotFound(NotFound):
-    # NOTE (dolph): metadata is not a user-facing concept,
-    # so this exception should not be exposed.
-
-    message_format = _("An unhandled exception has occurred:"
-                       " Could not find metadata.")
-
-
 class PolicyNotFound(NotFound):
     message_format = _("Could not find policy: %(policy_id)s")
 
@@ -371,10 +358,6 @@ class ProjectNotFound(NotFound):
     message_format = _("Could not find project: %(project_id)s")
 
 
-class InvalidParentProject(NotFound):
-    message_format = _("Cannot create project with parent: %(project_id)s")
-
-
 class TokenNotFound(NotFound):
     message_format = _("Could not find token: %(token_id)s")
 
@@ -442,12 +425,6 @@ class ConfigRegistrationNotFound(Exception):
     pass
 
 
-class KeystoneConfigurationError(Exception):
-    # This is an exception to be used in the case that Keystone config is
-    # invalid and Keystone should not start.
-    pass
-
-
 class Conflict(Error):
     message_format = _("Conflict occurred attempting to store %(type)s -"
                        " %(details)s")
@@ -579,10 +556,6 @@ class TokenlessAuthConfigError(ValidationError):
                        'was not found in the request environment.')
 
 
-class UnsupportedDriverVersion(UnexpectedError):
-    debug_message_format = _('%(driver)s is not supported driver version')
-
-
 class CredentialEncryptionError(Exception):
     message_format = _("An unexpected error prevented the server "
                        "from accessing encrypted credentials.")