diff --git a/django/contrib/sessions/backends/cache.py b/django/contrib/sessions/backends/cache.py
index c0d17ca45a..860d3a46c5 100644
--- a/django/contrib/sessions/backends/cache.py
+++ b/django/contrib/sessions/backends/cache.py
@@ -67,7 +67,7 @@ class SessionStore(SessionBase):
             raise CreateError
 
     def exists(self, session_key):
-        return session_key and (self.cache_key_prefix + session_key) in self._cache
+        return bool(session_key) and (self.cache_key_prefix + session_key) in self._cache
 
     def delete(self, session_key=None):
         if session_key is None:
diff --git a/tests/sessions_tests/tests.py b/tests/sessions_tests/tests.py
index 552b80daeb..b70df90834 100644
--- a/tests/sessions_tests/tests.py
+++ b/tests/sessions_tests/tests.py
@@ -348,7 +348,8 @@ class SessionTestsMixin:
         session = self.backend('someunknownkey')
         session.load()
 
-        self.assertFalse(session.exists(session.session_key))
+        self.assertIsNone(session.session_key)
+        self.assertIs(session.exists(session.session_key), False)
         # provided unknown key was cycled, not reused
         self.assertNotEqual(session.session_key, 'someunknownkey')