diff --git a/docs/en/docs/release-notes.md b/docs/en/docs/release-notes.md
index 0c7d44049..7658ab970 100644
--- a/docs/en/docs/release-notes.md
+++ b/docs/en/docs/release-notes.md
@@ -7,12 +7,21 @@ hide:
 
 ## Latest Changes
 
+### Features
+
+* 🚸 Improve error message for invalid query parameter type annotations. PR [#14479](https://github.com/fastapi/fastapi/pull/14479) by [@retwish](https://github.com/retwish).
+
+### Fixes
+
+* 🐛 Fix OpenAPI duplication of `anyOf` refs for app-level responses with specified `content` and `model` as `Union`. PR [#14463](https://github.com/fastapi/fastapi/pull/14463) by [@DJMcoder](https://github.com/DJMcoder).
+
 ### Refactors
 
 * 💡 Update comment for Pydantic internals. PR [#14814](https://github.com/fastapi/fastapi/pull/14814) by [@tiangolo](https://github.com/tiangolo).
 
 ### Docs
 
+* 📝 Add banner to translated pages. PR [#14809](https://github.com/fastapi/fastapi/pull/14809) by [@YuriiMotov](https://github.com/YuriiMotov).
 * 📝 Add links to related sections of docs to docstrings. PR [#14776](https://github.com/fastapi/fastapi/pull/14776) by [@YuriiMotov](https://github.com/YuriiMotov).
 * 📝 Update embedded code examples to Python 3.10 syntax. PR [#14758](https://github.com/fastapi/fastapi/pull/14758) by [@YuriiMotov](https://github.com/YuriiMotov).
 * 📝 Fix dependency installation command in `docs/en/docs/contributing.md`. PR [#14757](https://github.com/fastapi/fastapi/pull/14757) by [@YuriiMotov](https://github.com/YuriiMotov).
diff --git a/docs/en/docs/translation-banner.md b/docs/en/docs/translation-banner.md
new file mode 100644
index 000000000..142287074
--- /dev/null
+++ b/docs/en/docs/translation-banner.md
@@ -0,0 +1,11 @@
+/// details | 🌐 Translation by AI and humans
+
+This translation was made by AI guided by humans. 🤝
+
+It could have mistakes of misunderstanding the original meaning, or looking unnatural, etc. 🤖
+
+You can improve this translation by [helping us guide the AI LLM better](https://fastapi.tiangolo.com/contributing/#translations).
+
+[English version](ENGLISH_VERSION_URL)
+
+///
diff --git a/docs/ru/docs/translation-banner.md b/docs/ru/docs/translation-banner.md
new file mode 100644
index 000000000..78ebd676c
--- /dev/null
+++ b/docs/ru/docs/translation-banner.md
@@ -0,0 +1,11 @@
+/// details | 🌐 Перевод выполнен с помощью ИИ и людей
+
+Этот перевод был сделан ИИ под руководством людей. 🤝
+
+В нем могут быть ошибки из-за неправильного понимания оригинального смысла или неестественности и т. д. 🤖
+
+Вы можете улучшить этот перевод, [помогая нам лучше направлять ИИ LLM](https://fastapi.tiangolo.com/ru/contributing/#translations).
+
+[Английская версия](ENGLISH_VERSION_URL)
+
+///
diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index 2afc734ba..b647818c4 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -519,7 +519,7 @@ def analyze_param(
                     # For Pydantic v1
                     and getattr(field, "shape", 1) == 1
                 )
-            )
+            ), f"Query parameter {param_name!r} must be one of the supported types"
 
     return ParamDetails(type_annotation=type_annotation, depends=depends, field=field)
 
diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index 75ff26102..d56027b50 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -1,3 +1,4 @@
+import copy
 import http.client
 import inspect
 import warnings
@@ -377,7 +378,7 @@ def get_openapi_path(
                     additional_status_code,
                     additional_response,
                 ) in route.responses.items():
-                    process_response = additional_response.copy()
+                    process_response = copy.deepcopy(additional_response)
                     process_response.pop("model", None)
                     status_code_key = str(additional_status_code).upper()
                     if status_code_key == "DEFAULT":
diff --git a/scripts/mkdocs_hooks.py b/scripts/mkdocs_hooks.py
index 4b781270a..567c0111d 100644
--- a/scripts/mkdocs_hooks.py
+++ b/scripts/mkdocs_hooks.py
@@ -26,6 +26,17 @@ def get_missing_translation_content(docs_dir: str) -> str:
     return missing_translation_path.read_text(encoding="utf-8")
 
 
+@lru_cache
+def get_translation_banner_content(docs_dir: str) -> str:
+    docs_dir_path = Path(docs_dir)
+    translation_banner_path = docs_dir_path / "translation-banner.md"
+    if not translation_banner_path.is_file():
+        translation_banner_path = (
+            docs_dir_path.parent.parent / "en" / "docs" / "translation-banner.md"
+        )
+    return translation_banner_path.read_text(encoding="utf-8")
+
+
 @lru_cache
 def get_mkdocs_material_langs() -> list[str]:
     material_path = Path(material.__file__).parent
@@ -151,4 +162,21 @@ def on_page_markdown(
         if markdown.startswith("#"):
             header, _, body = markdown.partition("\n\n")
         return f"{header}\n\n{missing_translation_content}\n\n{body}"
-    return markdown
+
+    docs_dir_path = Path(config.docs_dir)
+    en_docs_dir_path = docs_dir_path.parent.parent / "en/docs"
+
+    if docs_dir_path == en_docs_dir_path:
+        return markdown
+
+    # For translated pages add translation banner
+    translation_banner_content = get_translation_banner_content(config.docs_dir)
+    en_url = "https://fastapi.tiangolo.com/" + page.url.lstrip("/")
+    translation_banner_content = translation_banner_content.replace(
+        "ENGLISH_VERSION_URL", en_url
+    )
+    header = ""
+    body = markdown
+    if markdown.startswith("#"):
+        header, _, body = markdown.partition("\n\n")
+    return f"{header}\n\n{translation_banner_content}\n\n{body}"
diff --git a/tests/test_additional_responses_union_duplicate_anyof.py b/tests/test_additional_responses_union_duplicate_anyof.py
new file mode 100644
index 000000000..f5d987ca3
--- /dev/null
+++ b/tests/test_additional_responses_union_duplicate_anyof.py
@@ -0,0 +1,123 @@
+"""
+Regression test: Ensure app-level responses with Union models and content/examples
+don't accumulate duplicate $ref entries in anyOf arrays.
+See https://github.com/fastapi/fastapi/pull/14463
+"""
+
+from typing import Union
+
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+from pydantic import BaseModel
+
+
+class ModelA(BaseModel):
+    a: str
+
+
+class ModelB(BaseModel):
+    b: str
+
+
+app = FastAPI(
+    responses={
+        500: {
+            "model": Union[ModelA, ModelB],
+            "content": {"application/json": {"examples": {"Case A": {"value": "a"}}}},
+        }
+    }
+)
+
+
+@app.get("/route1")
+async def route1():
+    pass  # pragma: no cover
+
+
+@app.get("/route2")
+async def route2():
+    pass  # pragma: no cover
+
+
+client = TestClient(app)
+
+
+def test_openapi_schema():
+    response = client.get("/openapi.json")
+    assert response.status_code == 200, response.text
+    assert response.json() == {
+        "openapi": "3.1.0",
+        "info": {"title": "FastAPI", "version": "0.1.0"},
+        "paths": {
+            "/route1": {
+                "get": {
+                    "summary": "Route1",
+                    "operationId": "route1_route1_get",
+                    "responses": {
+                        "200": {
+                            "description": "Successful Response",
+                            "content": {"application/json": {"schema": {}}},
+                        },
+                        "500": {
+                            "description": "Internal Server Error",
+                            "content": {
+                                "application/json": {
+                                    "schema": {
+                                        "anyOf": [
+                                            {"$ref": "#/components/schemas/ModelA"},
+                                            {"$ref": "#/components/schemas/ModelB"},
+                                        ],
+                                        "title": "Response 500 Route1 Route1 Get",
+                                    },
+                                    "examples": {"Case A": {"value": "a"}},
+                                }
+                            },
+                        },
+                    },
+                }
+            },
+            "/route2": {
+                "get": {
+                    "summary": "Route2",
+                    "operationId": "route2_route2_get",
+                    "responses": {
+                        "200": {
+                            "description": "Successful Response",
+                            "content": {"application/json": {"schema": {}}},
+                        },
+                        "500": {
+                            "description": "Internal Server Error",
+                            "content": {
+                                "application/json": {
+                                    "schema": {
+                                        "anyOf": [
+                                            {"$ref": "#/components/schemas/ModelA"},
+                                            {"$ref": "#/components/schemas/ModelB"},
+                                        ],
+                                        "title": "Response 500 Route2 Route2 Get",
+                                    },
+                                    "examples": {"Case A": {"value": "a"}},
+                                }
+                            },
+                        },
+                    },
+                }
+            },
+        },
+        "components": {
+            "schemas": {
+                "ModelA": {
+                    "properties": {"a": {"type": "string", "title": "A"}},
+                    "type": "object",
+                    "required": ["a"],
+                    "title": "ModelA",
+                },
+                "ModelB": {
+                    "properties": {"b": {"type": "string", "title": "B"}},
+                    "type": "object",
+                    "required": ["b"],
+                    "title": "ModelB",
+                },
+            }
+        },
+    }
diff --git a/tests/test_invalid_sequence_param.py b/tests/test_invalid_sequence_param.py
index 2b8fd059e..3695344f7 100644
--- a/tests/test_invalid_sequence_param.py
+++ b/tests/test_invalid_sequence_param.py
@@ -6,7 +6,10 @@ from pydantic import BaseModel
 
 
 def test_invalid_sequence():
-    with pytest.raises(AssertionError):
+    with pytest.raises(
+        AssertionError,
+        match="Query parameter 'q' must be one of the supported types",
+    ):
         app = FastAPI()
 
         class Item(BaseModel):
@@ -18,7 +21,10 @@ def test_invalid_sequence():
 
 
 def test_invalid_tuple():
-    with pytest.raises(AssertionError):
+    with pytest.raises(
+        AssertionError,
+        match="Query parameter 'q' must be one of the supported types",
+    ):
         app = FastAPI()
 
         class Item(BaseModel):
@@ -30,7 +36,10 @@ def test_invalid_tuple():
 
 
 def test_invalid_dict():
-    with pytest.raises(AssertionError):
+    with pytest.raises(
+        AssertionError,
+        match="Query parameter 'q' must be one of the supported types",
+    ):
         app = FastAPI()
 
         class Item(BaseModel):
@@ -42,7 +51,10 @@ def test_invalid_dict():
 
 
 def test_invalid_simple_dict():
-    with pytest.raises(AssertionError):
+    with pytest.raises(
+        AssertionError,
+        match="Query parameter 'q' must be one of the supported types",
+    ):
         app = FastAPI()
 
         class Item(BaseModel):