diff --git a/B05_Profile/B05_Profile_Api_Fetch.ts b/B05_Profile/B05_Profile_Api_Fetch.ts
index bd32c576d..653b11c7e 100644
--- a/B05_Profile/B05_Profile_Api_Fetch.ts
+++ b/B05_Profile/B05_Profile_Api_Fetch.ts
@@ -323,9 +323,9 @@ export async function flushRouteParts(projectId: string): Promise<void> {
     readRouteLatestCache(projectId) ?? (await fetchLatestRoute(projectId).catch(() => null));
   const surface = await fetchConfirmedSurface(projectId).catch(() => null);
   await saveRouteParts(projectId, {
-    filter_key: latest?.surface_params.source_filter,
-    method: latest?.surface_params.method,
-    smooth: latest?.surface_params.smooth,
+    filter_key: latest?.surface_params?.source_filter,
+    method: latest?.surface_params?.method,
+    smooth: latest?.surface_params?.smooth,
     surface_model_id: surface?.model_id ?? undefined,
     irregular_stations: [],
     uphill_overrides: uphillOverridesOf(projectId),
diff --git a/B05_Profile/B05_Profile_UI_Page_Latest.ts b/B05_Profile/B05_Profile_UI_Page_Latest.ts
index 0e2f6c9dc..348e18adb 100644
--- a/B05_Profile/B05_Profile_UI_Page_Latest.ts
+++ b/B05_Profile/B05_Profile_UI_Page_Latest.ts
@@ -40,9 +40,9 @@ export function createLatestSource(projectId: string) {
     [
       value.route?.id ?? "",
       value.route?.surface_model_id ?? "",
-      value.surface_params.source_filter,
-      value.surface_params.method,
-      String(value.surface_params.smooth),
+      value.surface_params?.source_filter,
+      value.surface_params?.method,
+      String(value.surface_params?.smooth),
     ].join("|");
 
   /**
@@ -72,7 +72,7 @@ export function panelValuesOf(next: RouteLatestResponse): Partial<RoutePanelValu
   const options = next.route_params?.options ?? {};
   const draft = readPageSettings(next.project_id);
   return {
-    contourInterval: next.surface_params.contour_interval_m,
+    contourInterval: next.surface_params?.contour_interval_m, // 없음(옛 · 시험 노선) = 패널 값 그대로
     gradeClass: options.grade_class as RoutePanelValues["gradeClass"] | undefined,
     stationInterval: next.route_params?.station_interval_m ?? undefined,
     crossSampleInterval: next.route_params?.cross_sample_interval_m ?? undefined,
diff --git a/resources/tester/helper_271_profile_settings.cjs b/resources/tester/helper_271_profile_settings.cjs
index b395b017a..048e38ee6 100644
--- a/resources/tester/helper_271_profile_settings.cjs
+++ b/resources/tester/helper_271_profile_settings.cjs
@@ -115,4 +115,9 @@ settings.writePageSettings(P, {
   station_display: { station: 0, cumulative: 0 },
 });
 out.draftOnly = apply(undefined);
+state.clearState("pagesettings", P);
+// 463 덧 — surface_params 없는 노선(옛 · 시험 · 막 만든 프로젝트) = 안 죽고 저장 설정대로 · 등고선 칸은 패널 값 그대로
+const bare = { project_id: P, route_params: { enforce_pipe_clearance: true } };
+out.noSurface = apply(bare);
+out.noSurfacePanel = latestApi.panelValuesOf(bare).contourInterval ?? null;
 console.log(JSON.stringify(out));
diff --git a/resources/tester/test_271_profile_settings.py b/resources/tester/test_271_profile_settings.py
index 784eb3c77..f5a914af4 100644
--- a/resources/tester/test_271_profile_settings.py
+++ b/resources/tester/test_271_profile_settings.py
@@ -89,3 +89,15 @@ def test_두_보기가_같은_함수로_얹음():
 def test_좌측_패널_상한도_같은_기준():
     part = src("B05_Profile", "B05_Profile_UI_Panel_Settings.ts")
     assert "return gradeLimitOf(currentSpeed(), terrain, parseOptional(maxGradePct));" in part
+
+
+def test_지표면_설정_없는_노선도_안_죽음(got):
+    # 463 덧 — latest 에 surface_params 없음(옛 · 시험 · 막 만든 프로젝트) = 종단도 기준은 저장 설정대로 · 등고선 칸 그대로
+    assert got["noSurface"] == {
+        "grade": 14,
+        "enforce": True,
+        "display": {"station": 0, "cumulative": 0},
+    }
+    assert got["noSurfacePanel"] is None
+    fetch = src("B05_Profile", "B05_Profile_Api_Fetch.ts")
+    assert "latest?.surface_params.source_filter" not in fetch  # [저장] 상단측 차례도 같은 꼴