--- django/http/response.py.orig	2020-07-08 14:34:42.776562458 +0200
+++ django/http/response.py	2020-07-08 14:35:56.454687322 +0200
@@ -197,8 +197,8 @@
         if httponly:
             self.cookies[key]['httponly'] = True
         if samesite:
-            if samesite.lower() not in ('lax', 'strict'):
-                raise ValueError('samesite must be "lax" or "strict".')
+            if samesite.lower() not in ('lax', 'strict', 'none'):
+                raise ValueError('samesite must be "lax", "strict", or "none", not "%s".' % samesite)
             self.cookies[key]['samesite'] = samesite
 
     def setdefault(self, key, value):