From e31a5c19ca4f3ec278842e4da53c88fcb605e636 Mon Sep 17 00:00:00 2001
From: Matt Brophy <matt@brophy.org>
Date: Wed, 3 Dec 2025 13:05:07 -0500
Subject: [PATCH 1/2] Detect and handle partial dataStrategy results

---
 .changeset/violet-needles-impress.md          |  5 ++
 .../dom/data-browser-router-test.tsx          | 73 +++++++++++++++++++
 packages/react-router/lib/router/router.ts    | 22 ++++++
 3 files changed, 100 insertions(+)
 create mode 100644 .changeset/violet-needles-impress.md

diff --git a/.changeset/violet-needles-impress.md b/.changeset/violet-needles-impress.md
new file mode 100644
index 0000000000..03ff10126e
--- /dev/null
+++ b/.changeset/violet-needles-impress.md
@@ -0,0 +1,5 @@
+---
+"react-router": patch
+---
+
+Handle `dataStrategy` implementations that return insufficient result sets by adding errors for routes without any available result
diff --git a/packages/react-router/__tests__/dom/data-browser-router-test.tsx b/packages/react-router/__tests__/dom/data-browser-router-test.tsx
index a4096258d3..e04f7d0716 100644
--- a/packages/react-router/__tests__/dom/data-browser-router-test.tsx
+++ b/packages/react-router/__tests__/dom/data-browser-router-test.tsx
@@ -7,6 +7,7 @@ import {
 } from "@testing-library/react";
 import * as React from "react";
 import type {
+  DataStrategyResult,
   ErrorResponse,
   Fetcher,
   Location,
@@ -420,6 +421,78 @@ function testDomRouter(
           </div>"
         `);
       });
+
+      it("clears the HydrateFallback when dataStrategy returns partial results during hydration", async () => {
+        let dfd = createDeferred<Record<string, DataStrategyResult>>();
+        let router = createTestRouter(
+          [
+            {
+              id: "root",
+              path: "/",
+              loader: true,
+              HydrateFallback: () => "Loading...",
+              Component: () => (
+                <>
+                  <h1>Root:{useLoaderData()}</h1>
+                  <Outlet />
+                </>
+              ),
+              ErrorBoundary: () => {
+                let error = useRouteError();
+                return (
+                  <pre>
+                    Root:
+                    {error instanceof Error ? error.message : (error as string)}
+                  </pre>
+                );
+              },
+              children: [
+                {
+                  id: "index",
+                  index: true,
+                  loader: true,
+                  Component: () => <h2>Index:{useLoaderData()}</h2>,
+                  ErrorBoundary: () => (
+                    <pre>Index:{useRouteError() as string}</pre>
+                  ),
+                },
+              ],
+            },
+          ],
+          {
+            dataStrategy: () => dfd.promise,
+          },
+        );
+        let { container } = render(<RouterProvider router={router} />);
+
+        expect(getHtml(container)).toMatchInlineSnapshot(`
+          "<div>
+            Loading...
+          </div>"
+        `);
+
+        // Resolve data strategy with only an error at the index route but nothing
+        // for the root route
+        await dfd.resolve({
+          index: {
+            type: "error",
+            result: "INDEX ERROR",
+          },
+        });
+        await tick();
+        await tick();
+
+        // The router stubs in an error for the root route to get out of
+        // displaying the HydrateFallback
+        expect(getHtml(container)).toMatchInlineSnapshot(`
+          "<div>
+            <pre>
+              Root:
+              No result returned from dataStrategy for route root
+            </pre>
+          </div>"
+        `);
+      });
     });
 
     describe("navigations", () => {
diff --git a/packages/react-router/lib/router/router.ts b/packages/react-router/lib/router/router.ts
index da9d2557fe..3eb91be276 100644
--- a/packages/react-router/lib/router/router.ts
+++ b/packages/react-router/lib/router/router.ts
@@ -3032,6 +3032,28 @@ export function createRouter(init: RouterInit): Router {
       return dataResults;
     }
 
+    // If they forgot to return a result for a match, and we don't have existing
+    // `loaderData`/`errors` for that match, then we add an error to trigger the
+    // error boundary since we don't have any `loaderData` and therefore can't
+    // render the `Component`
+    if (!isMutationMethod(request.method)) {
+      for (let match of matches) {
+        if (
+          match.shouldCallHandler() &&
+          !results.hasOwnProperty(match.route.id) &&
+          !state.loaderData.hasOwnProperty(match.route.id) &&
+          (!state.errors || !state.errors.hasOwnProperty(match.route.id))
+        ) {
+          results[match.route.id] = {
+            type: ResultType.error,
+            result: new Error(
+              `No result returned from dataStrategy for route ${match.route.id}`,
+            ),
+          };
+        }
+      }
+    }
+
     for (let [routeId, result] of Object.entries(results)) {
       if (isRedirectDataStrategyResult(result)) {
         let response = result.result as Response;

From 847a9173ae69903dae7d4e86080d84856d11f5b4 Mon Sep 17 00:00:00 2001
From: Matt Brophy <matt@brophy.org>
Date: Thu, 4 Dec 2025 10:36:20 -0500
Subject: [PATCH 2/2] Update order of operations to avoid uncessesary
 shouldRevalidate calls

---
 packages/react-router/lib/router/router.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/react-router/lib/router/router.ts b/packages/react-router/lib/router/router.ts
index 3eb91be276..21704898e6 100644
--- a/packages/react-router/lib/router/router.ts
+++ b/packages/react-router/lib/router/router.ts
@@ -3039,10 +3039,10 @@ export function createRouter(init: RouterInit): Router {
     if (!isMutationMethod(request.method)) {
       for (let match of matches) {
         if (
-          match.shouldCallHandler() &&
           !results.hasOwnProperty(match.route.id) &&
           !state.loaderData.hasOwnProperty(match.route.id) &&
-          (!state.errors || !state.errors.hasOwnProperty(match.route.id))
+          (!state.errors || !state.errors.hasOwnProperty(match.route.id)) &&
+          match.shouldCallHandler()
         ) {
           results[match.route.id] = {
             type: ResultType.error,