diff --git a/IPython/core/completerlib.py b/IPython/core/completerlib.py
index 7860cb6..0ca97e7 100644
--- a/IPython/core/completerlib.py
+++ b/IPython/core/completerlib.py
@@ -154,6 +154,17 @@ def is_importable(module, attr, only_modules):
     else:
         return not(attr[:2] == '__' and attr[-2:] == '__')
 
+def is_possible_submodule(module, attr):
+    try:
+        obj = getattr(module, attr)
+    except AttributeError:
+        # Is possilby an unimported submodule
+        return True
+    except TypeError:
+        # https://github.com/ipython/ipython/issues/9678
+        return False
+    return inspect.ismodule(obj)
+
 
 def try_import(mod: str, only_modules=False) -> List[str]:
     """
@@ -172,7 +183,12 @@ def try_import(mod: str, only_modules=False) -> List[str]:
         completions.extend( [attr for attr in dir(m) if
                              is_importable(m, attr, only_modules)])
 
-    completions.extend(getattr(m, '__all__', []))
+    m_all = getattr(m, "__all__", [])
+    if only_modules:
+        completions.extend(attr for attr in m_all if is_possible_submodule(m, attr))
+    else:
+        completions.extend(m_all)
+
     if m_is_init:
         completions.extend(module_list(os.path.dirname(m.__file__)))
     completions_set = {c for c in completions if isinstance(c, str)}
diff --git a/IPython/core/tests/test_completerlib.py b/IPython/core/tests/test_completerlib.py
index d112704..f87e784 100644
--- a/IPython/core/tests/test_completerlib.py
+++ b/IPython/core/tests/test_completerlib.py
@@ -157,6 +157,11 @@ def test_bad_module_all():
         nt.assert_in('puppies', results)
         for r in results:
             nt.assert_is_instance(r, str)
+
+        # bad_all doesn't contain submodules, but this completion
+        # should finish without raising an exception:
+        results = module_completion("import bad_all.")
+        nt.assert_equal(results, [])
     finally:
         sys.path.remove(testsdir)
 
@@ -176,3 +181,14 @@ def test_module_without_init():
             assert s == []
         finally:
             sys.path.remove(tmpdir)
+
+
+def test_valid_exported_submodules():
+    """
+    Test checking exported (__all__) objects are submodules
+    """
+    results = module_completion("import os.pa")
+    # ensure we get a valid submodule:
+    nt.assert_in("os.path", results)
+    # ensure we don't get objects that aren't submodules:
+    nt.assert_not_in("os.pathconf", results)