diff --git a/oslo_versionedobjects/base.py b/oslo_versionedobjects/base.py
index 494b73a8..542d3fe7 100644
--- a/oslo_versionedobjects/base.py
+++ b/oslo_versionedobjects/base.py
@@ -30,7 +30,6 @@ from oslo_versionedobjects._i18n import _
 from oslo_versionedobjects import exception
 from oslo_versionedobjects import fields as obj_fields
 
-
 LOG = logging.getLogger('object')
 
 
@@ -386,12 +385,9 @@ class VersionedObject:
     def obj_class_from_name(cls, objname, objver):
         """Returns a class from the registry based on a name and version."""
         if objname not in VersionedObjectRegistry.obj_classes():
-            (
-                LOG.error(
-                    'Unable to instantiate unregistered object type '
-                    '%(objtype)s'
-                ),
-                dict(objtype=objname),
+            LOG.error(
+                'Unable to instantiate unregistered object type %(objtype)s',
+                {'objtype': objname},
             )
             raise exception.UnsupportedObjectError(objtype=objname)
 
diff --git a/oslo_versionedobjects/fields.py b/oslo_versionedobjects/fields.py
index 97e7c8ff..d9911454 100644
--- a/oslo_versionedobjects/fields.py
+++ b/oslo_versionedobjects/fields.py
@@ -385,14 +385,14 @@ class UUID(StringPattern):
                 # This is to ensure no breaking behaviour for current
                 # users
                 warnings.warn(
-                    "{} is an invalid UUID. Using UUIDFields "
-                    "with invalid UUIDs is no longer "
-                    "supported, and will be removed in a future "
-                    "release. Please update your "
-                    "code to input valid UUIDs or accept "
-                    "ValueErrors for invalid UUIDs. See "
-                    "https://docs.openstack.org/oslo.versionedobjects/latest/reference/fields.html#oslo_versionedobjects.fields.UUIDField "  # noqa
-                    "for further details".format(repr(value).encode('utf8')),
+                    f"{value!r} is an invalid UUID. Using UUIDFields "
+                    f"with invalid UUIDs is no longer "
+                    f"supported, and will be removed in a future "
+                    f"release. Please update your "
+                    f"code to input valid UUIDs or accept "
+                    f"ValueErrors for invalid UUIDs. See "
+                    f"https://docs.openstack.org/oslo.versionedobjects/latest/reference/fields.html#oslo_versionedobjects.fields.UUIDField "  # noqa
+                    f"for further details",
                     FutureWarning,
                 )