diff --git a/supervisor/api/store.py b/supervisor/api/store.py
index 92c58a69b58..82e14627f55 100644
--- a/supervisor/api/store.py
+++ b/supervisor/api/store.py
@@ -76,13 +76,16 @@ def _extract_addon(self, request: web.Request, installed=False) -> AnyAddon:
         addon_slug: str = request.match_info.get("addon")
 
         if not (addon := self.sys_addons.get(addon_slug)):
-            raise APINotFound(f"Addon {addon_slug} does not exist in the store")
+            raise APINotFound(f"Addon {addon_slug} does not exist")
 
         if installed and not addon.is_installed:
             raise APIError(f"Addon {addon_slug} is not installed")
 
         if not installed and addon.is_installed:
+            if not addon.addon_store:
+                raise APINotFound(f"Addon {addon_slug} does not exist in the store")
             return addon.addon_store
+
         return addon
 
     def _extract_repository(self, request: web.Request) -> Repository:
diff --git a/tests/api/test_jobs.py b/tests/api/test_jobs.py
index 298f350d911..00e798e227b 100644
--- a/tests/api/test_jobs.py
+++ b/tests/api/test_jobs.py
@@ -216,7 +216,7 @@ async def test_job_manual_cleanup(self) -> None:
     resp = await api_client.get(f"/jobs/{test.job_id}")
     assert resp.status == 404
     result = await resp.json()
-    assert result["message"] == f"No job found with id {test.job_id}"
+    assert result["message"] == "Job does not exist"
 
 
 @pytest.mark.parametrize(
diff --git a/tests/api/test_mounts.py b/tests/api/test_mounts.py
index 367c7c33d90..e22dcbb8763 100644
--- a/tests/api/test_mounts.py
+++ b/tests/api/test_mounts.py
@@ -264,25 +264,6 @@ async def test_api_update_mount(
     coresys.mounts.save_data.assert_called_once()
 
 
-async def test_api_update_error_mount_missing(
-    api_client: TestClient, mount_propagation
-):
-    """Test update mount API errors when mount does not exist."""
-    resp = await api_client.put(
-        "/mounts/backup_test",
-        json={
-            "type": "cifs",
-            "usage": "backup",
-            "server": "backup.local",
-            "share": "new_backups",
-        },
-    )
-    assert resp.status == 400
-    result = await resp.json()
-    assert result["result"] == "error"
-    assert result["message"] == "No mount exists with name backup_test"
-
-
 async def test_api_update_dbus_error_mount_remains(
     api_client: TestClient,
     all_dbus_services: dict[str, DBusServiceMock],
@@ -399,20 +380,6 @@ async def test_api_reload_mount(
     ]
 
 
-async def test_api_reload_error_mount_missing(
-    api_client: TestClient, mount_propagation
-):
-    """Test reload mount API errors when mount does not exist."""
-    resp = await api_client.post("/mounts/backup_test/reload")
-    assert resp.status == 400
-    result = await resp.json()
-    assert result["result"] == "error"
-    assert (
-        result["message"]
-        == "Cannot reload 'backup_test', no mount exists with that name"
-    )
-
-
 async def test_api_delete_mount(
     api_client: TestClient,
     coresys: CoreSys,
@@ -435,20 +402,6 @@ async def test_api_delete_mount(
     coresys.mounts.save_data.assert_called_once()
 
 
-async def test_api_delete_error_mount_missing(
-    api_client: TestClient, mount_propagation
-):
-    """Test delete mount API errors when mount does not exist."""
-    resp = await api_client.delete("/mounts/backup_test")
-    assert resp.status == 400
-    result = await resp.json()
-    assert result["result"] == "error"
-    assert (
-        result["message"]
-        == "Cannot remove 'backup_test', no mount exists with that name"
-    )
-
-
 async def test_api_create_backup_mount_sets_default(
     api_client: TestClient,
     coresys: CoreSys,
@@ -903,3 +856,19 @@ async def test_api_read_only_backup_mount_invalid(
     result = await resp.json()
     assert result["result"] == "error"
     assert "Backup mounts cannot be read only" in result["message"]
+
+
+@pytest.mark.parametrize(
+    ("method", "url"),
+    [
+        ("put", "/mounts/bad"),
+        ("delete", "/mounts/bad"),
+        ("post", "/mounts/bad/reload"),
+    ],
+)
+async def test_mount_not_found(api_client: TestClient, method: str, url: str):
+    """Test mount not found error."""
+    resp = await api_client.request(method, url)
+    assert resp.status == 404
+    resp = await resp.json()
+    assert resp["message"] == "No mount exists with name bad"
diff --git a/tests/api/test_store.py b/tests/api/test_store.py
index f571c2ad8fb..0a11df9b02a 100644
--- a/tests/api/test_store.py
+++ b/tests/api/test_store.py
@@ -236,7 +236,7 @@ async def test_api_detached_addon_changelog(
     resp = await api_client.get(f"/{resource}/{install_addon_ssh.slug}/changelog")
     assert resp.status == 200
     result = await resp.text()
-    assert result == "Addon local_ssh with version latest does not exist in the store"
+    assert result == "Addon local_ssh does not exist in the store"
 
 
 @pytest.mark.parametrize("resource", ["store/addons", "addons"])
@@ -280,7 +280,7 @@ async def test_api_detached_addon_documentation(
     resp = await api_client.get(f"/{resource}/{install_addon_ssh.slug}/documentation")
     assert resp.status == 200
     result = await resp.text()
-    assert result == "Addon local_ssh with version latest does not exist in the store"
+    assert result == "Addon local_ssh does not exist in the store"
 
 
 async def get_message(resp: ClientResponse, json_expected: bool) -> str:
@@ -315,10 +315,7 @@ async def test_store_addon_not_found(
     """Test store addon not found error."""
     resp = await api_client.request(method, url)
     assert resp.status == 404
-    assert (
-        await get_message(resp, json_expected)
-        == "Addon bad does not exist in the store"
-    )
+    assert await get_message(resp, json_expected) == "Addon bad does not exist"
 
 
 @pytest.mark.parametrize(