Fixed #21497 -- Forced conversion to bytes for very long index names

django/db/backends/schema.py

@@ -5,6 +5,7 @@ from django.db.backends.creation import BaseDatabaseCreation
 from django.db.backends.utils import truncate_name
 from django.db.models.fields.related import ManyToManyField
 from django.db.transaction import atomic
+from django.utils.encoding import force_bytes
 from django.utils.log import getLogger
 from django.utils.six.moves import reduce
 from django.utils.six import callable
@@ -703,7 +704,7 @@ class BaseDatabaseSchemaEditor(object):
             index_name = index_name[1:]
         # If it's STILL too long, just hash it down
         if len(index_name) > self.connection.features.max_index_name_length:
-            index_name = hashlib.md5(index_name).hexdigest()[:self.connection.features.max_index_name_length]
+            index_name = hashlib.md5(force_bytes(index_name)).hexdigest()[:self.connection.features.max_index_name_length]
         # It can't start with a number on Oracle, so prepend D if we need to
         if index_name[0].isdigit():
             index_name = "D%s" % index_name[:-1]