From b88f868e50e1b12569211c240518e8517f2ebe90 Mon Sep 17 00:00:00 2001
From: Simon Huang <simon.huang@telecom-st-etienne.fr>
Date: Mon, 8 Dec 2025 19:27:50 +0100
Subject: [PATCH 1/4] Make the logic more explicit in validation error
 insertion in get_open_api_path

---
 fastapi/openapi/utils.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index 06c14861a..53333b664 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -417,10 +417,12 @@ def get_openapi_path(
                     openapi_response["description"] = description
             http422 = "422"
             all_route_params = get_flat_params(route.dependant)
-            if (all_route_params or route.body_field) and not any(
-                status in operation["responses"]
-                for status in [http422, "4XX", "default"]
-            ):
+            requires_validation_error = bool(all_route_params or route.body_field)
+            has_validation_response = any(
+                status in operation["responses"] 
+                for status in ("422", "4XX", "default")
+            )
+            if requires_validation_error and not has_validation_response:
                 operation["responses"][http422] = {
                     "description": "Validation Error",
                     "content": {

From e7f361cacb8f0715c2ae6021511176fd46a88806 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci-lite[bot]"
 <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Date: Mon, 8 Dec 2025 18:32:30 +0000
Subject: [PATCH 2/4] =?UTF-8?q?=F0=9F=8E=A8=20Auto=20format?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 fastapi/openapi/utils.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index 53333b664..88786087a 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -419,8 +419,7 @@ def get_openapi_path(
             all_route_params = get_flat_params(route.dependant)
             requires_validation_error = bool(all_route_params or route.body_field)
             has_validation_response = any(
-                status in operation["responses"] 
-                for status in ("422", "4XX", "default")
+                status in operation["responses"] for status in ("422", "4XX", "default")
             )
             if requires_validation_error and not has_validation_response:
                 operation["responses"][http422] = {

From aa87c18e114ac0d3c08dfda2bcd4f046084e935b Mon Sep 17 00:00:00 2001
From: Simon Huang <simon.huang@telecom-st-etienne.fr>
Date: Mon, 8 Dec 2025 19:27:50 +0100
Subject: [PATCH 3/4] Make the logic more explicit in validation error
 insertion in get_open_api_path

---
 fastapi/openapi/utils.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index 06c14861a..88786087a 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -417,10 +417,11 @@ def get_openapi_path(
                     openapi_response["description"] = description
             http422 = "422"
             all_route_params = get_flat_params(route.dependant)
-            if (all_route_params or route.body_field) and not any(
-                status in operation["responses"]
-                for status in [http422, "4XX", "default"]
-            ):
+            requires_validation_error = bool(all_route_params or route.body_field)
+            has_validation_response = any(
+                status in operation["responses"] for status in ("422", "4XX", "default")
+            )
+            if requires_validation_error and not has_validation_response:
                 operation["responses"][http422] = {
                     "description": "Validation Error",
                     "content": {

From 6aebae99271e280bf7d26d6c71026f2ef324f1e3 Mon Sep 17 00:00:00 2001
From: Simon-Huang-1 <72698744+Simon-Huang-1@users.noreply.github.com>
Date: Tue, 9 Dec 2025 18:37:17 +0100
Subject: [PATCH 4/4] Update fastapi/openapi/utils.py

Co-authored-by: Motov Yurii <109919500+YuriiMotov@users.noreply.github.com>
---
 fastapi/openapi/utils.py | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index 88786087a..9d5c98e88 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -417,11 +417,13 @@ def get_openapi_path(
                     openapi_response["description"] = description
             http422 = "422"
             all_route_params = get_flat_params(route.dependant)
-            requires_validation_error = bool(all_route_params or route.body_field)
-            has_validation_response = any(
-                status in operation["responses"] for status in ("422", "4XX", "default")
-            )
-            if requires_validation_error and not has_validation_response:
+            if (
+                (all_route_params or route.body_field)  # May raise validation error
+                and not any(  # Doesn't have a defined validation error response already
+                    status in operation["responses"]
+                    for status in [http422, "4XX", "default"]
+                )
+            ):
                 operation["responses"][http422] = {
                     "description": "Validation Error",
                     "content": {