diff --git a/news/21.bugfix b/news/21.bugfix
new file mode 100644
index 0000000..a5e9820
--- /dev/null
+++ b/news/21.bugfix
@@ -0,0 +1,2 @@
+Fix ``TypeError`` in the sharing view when two role entries tie on
+``(sticky, type, name)``; [jmevissen]
diff --git a/src/plone/app/workflow/browser/sharing.py b/src/plone/app/workflow/browser/sharing.py
index ceacc2b..600b5ee 100644
--- a/src/plone/app/workflow/browser/sharing.py
+++ b/src/plone/app/workflow/browser/sharing.py
@@ -285,7 +285,10 @@ def existing_role_settings(self):
             (a["id"] not in self.STICKY, a["type"], a["name"], a)
             for a in items.values()
         ]
-        dec_users.sort()
+        # Sort only on the first three entries,
+        # the fourth is a dict and would raise a TypeError
+        # see plone/plone.app.workflow#21
+        dec_users.sort(key=lambda d: (d[0], d[1], d[2]))
 
         # Add the items to the info dict, assigning full name if possible.
         # Also, recut roles in the format specified in the docstring
diff --git a/src/plone/app/workflow/tests/test_sharing_view.py b/src/plone/app/workflow/tests/test_sharing_view.py
index df11b1b..23416e9 100644
--- a/src/plone/app/workflow/tests/test_sharing_view.py
+++ b/src/plone/app/workflow/tests/test_sharing_view.py
@@ -234,3 +234,26 @@ def lrme_handler(context, event):
         # check subscriber called
         self.assertEqual(context.context, context)
         self.assertEqual(context.event, event)
+
+    def test_existing_role_settings_sort_with_duplicate_names(self):
+        """Regression test for plone/plone.app.workflow#21.
+
+        When two entries tie on (sticky, type, name), the old
+        ``dec_users.sort()`` fell through to comparing the item dicts at
+        index 3, raising ``TypeError: '<' not supported between instances
+        of 'dict' and 'dict'`` on Python 3.
+        """
+        login(self.portal, "manager")
+        sharing = getMultiAdapter((self.portal, self.request), name="sharing")
+
+        def fake_inherited_roles():
+            return (
+                ("shared_name", ("Reader",), "user", "user_a"),
+                ("shared_name", ("Reader",), "user", "user_b"),
+            )
+
+        sharing._inherited_roles = fake_inherited_roles
+        info = sharing.existing_role_settings()
+        ids = {entry["id"] for entry in info}
+        self.assertIn("user_a", ids)
+        self.assertIn("user_b", ids)