diff --git a/src/ndev_settings/_settings.py b/src/ndev_settings/_settings.py
index 2087040..798ace9 100644
--- a/src/ndev_settings/_settings.py
+++ b/src/ndev_settings/_settings.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import hashlib
+import importlib.metadata as importlib_metadata
 import logging
 from importlib.metadata import entry_points
 from pathlib import Path
@@ -33,10 +34,27 @@ def _load_yaml(path: Path) -> dict:
 def _get_entry_points_hash() -> str:
     """Generate a hash of installed ndev_settings.manifest entry points.
 
-    Used to detect when packages are installed/removed.
+    Used to detect when contributed settings schemas may have changed.
+    Package versions are included so upgrading a contributing package
+    invalidates the cache even when the entry point string itself is stable.
     """
-    eps = entry_points(group="ndev_settings.manifest")
-    ep_strings = sorted(f"{ep.name}:{ep.value}" for ep in eps)
+    eps = sorted(
+        entry_points(group="ndev_settings.manifest"),
+        key=lambda ep: (ep.name, ep.value),
+    )
+    ep_strings = []
+    for ep in eps:
+        package_name, _, _ = ep.value.partition(":")
+        try:
+            dist = importlib_metadata.distribution(package_name)
+            package_version = getattr(dist, "version", "unknown")
+        except (
+            importlib_metadata.PackageNotFoundError,
+            ValueError,
+            OSError,
+        ):
+            package_version = "unknown"
+        ep_strings.append(f"{ep.name}:{ep.value}:{package_version}")
     return hashlib.sha256("|".join(ep_strings).encode()).hexdigest()
 
 
@@ -114,9 +132,7 @@ def _load_defaults(self) -> dict:
 
                 # Use distribution() to find package location WITHOUT importing it
                 # This avoids slow package imports (e.g., ndevio takes 2.5s to import)
-                from importlib.metadata import distribution
-
-                dist = distribution(package_name)
+                dist = importlib_metadata.distribution(package_name)
                 yaml_path = None
 
                 # For regular installs, dist.files contains the file list
@@ -184,6 +200,7 @@ def _load_defaults(self) -> dict:
                         if name not in all_settings[group_name]:
                             all_settings[group_name][name] = data
             except (
+                importlib_metadata.PackageNotFoundError,
                 ModuleNotFoundError,
                 FileNotFoundError,
                 ValueError,
diff --git a/tests/test_settings.py b/tests/test_settings.py
index 756b5d9..6e0d8aa 100644
--- a/tests/test_settings.py
+++ b/tests/test_settings.py
@@ -220,6 +220,94 @@ def test_package_change_preserves_user_values(
         # User's custom value should be preserved
         assert settings2.Group_A.setting_int == 777
 
+    def test_package_upgrade_backfills_new_settings(
+        self, test_settings_file, tmp_path, monkeypatch
+    ):
+        """Upgrading a contributing package should invalidate the cache.
+
+        This covers the common case where a package keeps the same
+        ``ndev_settings.manifest`` entry point but ships a new setting in its
+        YAML schema in a later version.
+        """
+        import yaml
+
+        external_file = tmp_path / "external.yaml"
+        version_state = {"value": "1.0.0"}
+
+        external_v1 = {
+            "External_Group": {
+                "existing_setting": {
+                    "value": 10,
+                    "default": 10,
+                }
+            }
+        }
+        external_v2 = {
+            "External_Group": {
+                "existing_setting": {
+                    "value": 10,
+                    "default": 10,
+                },
+                "new_setting": {
+                    "value": 42,
+                    "default": 42,
+                },
+            }
+        }
+        external_file.write_text(yaml.dump(external_v1))
+
+        class MockEntryPoint:
+            def __init__(self):
+                self.name = "mock_external"
+                self.value = "mock_package:settings.yaml"
+
+        class MockPackagePath:
+            def __init__(self, actual_path):
+                self._path = actual_path
+                self.name = "settings.yaml"
+
+            def __str__(self):
+                return "mock_package/settings.yaml"
+
+        class MockDistribution:
+            def __init__(self):
+                self.version = version_state["value"]
+                self.files = [MockPackagePath(external_file)]
+
+            def locate_file(self, file):
+                return file._path
+
+        from importlib.metadata import distribution as orig_distribution
+
+        def mock_entry_points(group=None):
+            if group == "ndev_settings.manifest":
+                return [MockEntryPoint()]
+            return []
+
+        def mock_distribution(name):
+            if name == "mock_package":
+                return MockDistribution()
+            return orig_distribution(name)
+
+        monkeypatch.setattr(
+            "ndev_settings._settings.entry_points", mock_entry_points
+        )
+        monkeypatch.setattr(
+            "importlib.metadata.distribution", mock_distribution
+        )
+
+        settings1 = Settings(str(test_settings_file))
+        settings1.External_Group.existing_setting = 777
+        settings1.save()
+
+        external_file.write_text(yaml.dump(external_v2))
+        version_state["value"] = "2.0.0"
+
+        settings2 = Settings(str(test_settings_file))
+
+        assert settings2.External_Group.existing_setting == 777
+        assert settings2.External_Group.new_setting == 42
+
     def test_clear_settings_handles_missing_file(self):
         """Test that clear_settings doesn't crash if file doesn't exist."""
         from ndev_settings import _settings