diff --git a/Lib/idlelib/autocomplete.py b/Lib/idlelib/autocomplete.py
index 032d31225315fb..b07e10ac24e46b 100644
--- a/Lib/idlelib/autocomplete.py
+++ b/Lib/idlelib/autocomplete.py
@@ -186,7 +186,8 @@ def fetch_completions(self, what, mode):
                     bigl.extend(completion_kwds)
                     bigl.sort()
                     if "__all__" in bigl:
-                        smalll = sorted(eval("__all__", namespace))
+                        all_val = eval("__all__", namespace)
+                        smalll = sorted(all_val) if hasattr(all_val, "__iter__") else [s for s in bigl if s[:1] != "_"]
                     else:
                         smalll = [s for s in bigl if s[:1] != '_']
                 else:
@@ -195,7 +196,8 @@ def fetch_completions(self, what, mode):
                         bigl = dir(entity)
                         bigl.sort()
                         if "__all__" in bigl:
-                            smalll = sorted(entity.__all__)
+                            all_val = entity.__all__
+                            smalll = sorted(all_val) if hasattr(all_val, "__iter__") else [s for s in bigl if s[:1] != "_"]
                         else:
                             smalll = [s for s in bigl if s[:1] != '_']
                     except:
diff --git a/Misc/NEWS.d/next/IDLE/2026-07-11-00-00-00.gh-issue-153506.xYzAbC.rst b/Misc/NEWS.d/next/IDLE/2026-07-11-00-00-00.gh-issue-153506.xYzAbC.rst
new file mode 100644
index 00000000000000..90b9d7716b45de
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2026-07-11-00-00-00.gh-issue-153506.xYzAbC.rst
@@ -0,0 +1,3 @@
+Fix IDLE shell crash when Tab-completing in a module with a non-iterable
+``__all__`` attribute (e.g. ``__all__ = None``). The shell now falls back
+to standard completion instead of raising :exc:`TypeError`.