diff --git a/django/utils/autoreload.py b/django/utils/autoreload.py
index e7c9acbaea..cf2cefeea9 100644
--- a/django/utils/autoreload.py
+++ b/django/utils/autoreload.py
@@ -40,6 +40,7 @@ from django.conf import settings
 from django.core.signals import request_finished
 from django.utils import six
 from django.utils._os import npath
+from django.utils.encoding import force_bytes, get_system_encoding
 from django.utils.six.moves import _thread as thread
 
 # This import does nothing, but it's necessary to avoid some race conditions
@@ -285,6 +286,14 @@ def restart_with_reloader():
     while True:
         args = [sys.executable] + ['-W%s' % o for o in sys.warnoptions] + sys.argv
         new_environ = os.environ.copy()
+        if _win and six.PY2:
+            # Environment variables on Python 2 + Windows must be str.
+            encoding = get_system_encoding()
+            for key in new_environ.keys():
+                str_key = force_bytes(key, encoding=encoding)
+                str_value = force_bytes(new_environ[key], encoding=encoding)
+                del new_environ[key]
+                new_environ[str_key] = str_value
         new_environ["RUN_MAIN"] = 'true'
         exit_code = subprocess.call(args, env=new_environ)
         if exit_code != 3:
diff --git a/docs/releases/1.11.4.txt b/docs/releases/1.11.4.txt
index 2cd093335e..9448611ecc 100644
--- a/docs/releases/1.11.4.txt
+++ b/docs/releases/1.11.4.txt
@@ -18,3 +18,6 @@ Bugfixes
 
 * Fixed a regression in pickling of ``LazyObject`` on Python 2 when the wrapped
   object doesn't have ``__reduce__()`` (:ticket:`28389`).
+
+* Fixed crash in ``runserver``'s ``autoreload`` with Python 2 on Windows with
+  non-``str`` environment variables (:ticket:`28174`).
diff --git a/tests/utils_tests/test_autoreload.py b/tests/utils_tests/test_autoreload.py
index 5d42af62c8..3fae2e4da2 100644
--- a/tests/utils_tests/test_autoreload.py
+++ b/tests/utils_tests/test_autoreload.py
@@ -1,6 +1,9 @@
+from __future__ import unicode_literals
+
 import gettext
 import os
 import shutil
+import sys
 import tempfile
 from importlib import import_module
 
@@ -251,3 +254,17 @@ class ResetTranslationsTests(SimpleTestCase):
         self.assertEqual(trans_real._translations, {})
         self.assertIsNone(trans_real._default)
         self.assertIsInstance(trans_real._active, _thread._local)
+
+
+class TestRestartWithReloader(SimpleTestCase):
+
+    def test_environment(self):
+        """"
+        With Python 2 on Windows, restart_with_reloader() coerces environment
+        variables to str to avoid "TypeError: environment can only contain
+        strings" in Python's subprocess.py.
+        """
+        # With unicode_literals, these values are unicode.
+        os.environ['SPAM'] = 'spam'
+        with mock.patch.object(sys, 'argv', ['-c', 'pass']):
+            autoreload.restart_with_reloader()