From 37b2f73452814f179d853d306c0bbcc3b3b7af42 Mon Sep 17 00:00:00 2001
From: viva-jake <jake@adoc.co.kr>
Date: Mon, 20 Jan 2025 18:02:34 +0900
Subject: [PATCH 1/3] update useSearchParams to handle function input correctly
 by passing URLSearchParams instance

---
 packages/react-router/lib/dom/lib.tsx | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/react-router/lib/dom/lib.tsx b/packages/react-router/lib/dom/lib.tsx
index 821b6a6457..53c434152e 100644
--- a/packages/react-router/lib/dom/lib.tsx
+++ b/packages/react-router/lib/dom/lib.tsx
@@ -1378,7 +1378,9 @@ export function useSearchParams(
   let setSearchParams = React.useCallback<SetURLSearchParams>(
     (nextInit, navigateOptions) => {
       const newSearchParams = createSearchParams(
-        typeof nextInit === "function" ? nextInit(searchParams) : nextInit
+        typeof nextInit === "function"
+          ? nextInit(new URLSearchParams(searchParams))
+          : nextInit
       );
       hasSetSearchParamsRef.current = true;
       navigate("?" + newSearchParams, navigateOptions);

From 518c2dfd12e0bc7bfbacab16f1c2c5375a674bb7 Mon Sep 17 00:00:00 2001
From: viva-jake <jake@adoc.co.kr>
Date: Mon, 20 Jan 2025 18:23:47 +0900
Subject: [PATCH 2/3] add name to contributors.yml

---
 contributors.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/contributors.yml b/contributors.yml
index a7a7476510..ff908f6635 100644
--- a/contributors.yml
+++ b/contributors.yml
@@ -334,6 +334,7 @@
 - yionr
 - yracnet
 - ytori
+- yuhwan-park
 - yuleicul
 - zeromask1337
 - zheng-chuang

From 6ae48899eff52f0b425701b1d88ad9d1f77a720e Mon Sep 17 00:00:00 2001
From: Matt Brophy <matt@brophy.org>
Date: Mon, 30 Jun 2025 15:54:30 -0400
Subject: [PATCH 3/3] Add changeset and test

---
 .changeset/curly-sloths-end.md                |   5 +
 .../__tests__/dom/search-params-test.tsx      | 114 +++++++++++++++++-
 2 files changed, 118 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/curly-sloths-end.md

diff --git a/.changeset/curly-sloths-end.md b/.changeset/curly-sloths-end.md
new file mode 100644
index 0000000000..b89d7ea688
--- /dev/null
+++ b/.changeset/curly-sloths-end.md
@@ -0,0 +1,5 @@
+---
+"react-router": patch
+---
+
+Pass a copy of `searchParams` to the `setSearchParams` callback function to avoid muations of the internal `searchParams` instance. This was an issue when navigations were blocked because the internal instance be out of sync with `useLocation().search`.
diff --git a/packages/react-router/__tests__/dom/search-params-test.tsx b/packages/react-router/__tests__/dom/search-params-test.tsx
index 7afece9c34..e8ddbc586f 100644
--- a/packages/react-router/__tests__/dom/search-params-test.tsx
+++ b/packages/react-router/__tests__/dom/search-params-test.tsx
@@ -1,7 +1,16 @@
 import * as React from "react";
 import * as ReactDOM from "react-dom/client";
 import { act } from "react-dom/test-utils";
-import { MemoryRouter, Routes, Route, useSearchParams } from "../../index";
+import {
+  MemoryRouter,
+  Routes,
+  Route,
+  useSearchParams,
+  createBrowserRouter,
+  useBlocker,
+  RouterProvider,
+  useLocation,
+} from "../../index";
 
 describe("useSearchParams", () => {
   let node: HTMLDivElement;
@@ -182,4 +191,107 @@ describe("useSearchParams", () => {
       `"<p>value=initial&amp;a=1&amp;b=2</p>"`
     );
   });
+
+  it("does not reflect functional update mutation when navigation is blocked", () => {
+    let router = createBrowserRouter([
+      {
+        path: "/",
+        Component() {
+          let location = useLocation();
+          let [searchParams, setSearchParams] = useSearchParams();
+          let [shouldBlock, setShouldBlock] = React.useState(false);
+          let b = useBlocker(shouldBlock);
+          return (
+            <>
+              <pre id="output">
+                {`location.search=${location.search}`}
+                {`searchParams=${searchParams.toString()}`}
+                {`blocked=${b.state}`}
+              </pre>
+              <button
+                id="toggle-blocking"
+                onClick={() => setShouldBlock(!shouldBlock)}
+              >
+                Toggle Blocking
+              </button>
+              <button
+                id="navigate1"
+                onClick={() => {
+                  setSearchParams((prev) => {
+                    prev.set("foo", "bar");
+                    return prev;
+                  });
+                }}
+              >
+                Navigate 1
+              </button>
+              <button
+                id="navigate2"
+                onClick={() => {
+                  setSearchParams((prev) => {
+                    prev.set("foo", "baz");
+                    return prev;
+                  });
+                }}
+              >
+                Navigate 2
+              </button>
+            </>
+          );
+        },
+      },
+    ]);
+
+    act(() => {
+      ReactDOM.createRoot(node).render(<RouterProvider router={router} />);
+    });
+
+    expect(node.querySelector("#output")).toMatchInlineSnapshot(`
+      <pre
+        id="output"
+      >
+        location.search=
+        searchParams=
+        blocked=unblocked
+      </pre>
+    `);
+
+    act(() => {
+      node
+        .querySelector("#navigate1")!
+        .dispatchEvent(new Event("click", { bubbles: true }));
+    });
+
+    expect(node.querySelector("#output")).toMatchInlineSnapshot(`
+      <pre
+        id="output"
+      >
+        location.search=?foo=bar
+        searchParams=foo=bar
+        blocked=unblocked
+      </pre>
+    `);
+
+    act(() => {
+      node
+        .querySelector("#toggle-blocking")!
+        .dispatchEvent(new Event("click", { bubbles: true }));
+    });
+
+    act(() => {
+      node
+        .querySelector("#navigate2")!
+        .dispatchEvent(new Event("click", { bubbles: true }));
+    });
+
+    expect(node.querySelector("#output")).toMatchInlineSnapshot(`
+      <pre
+        id="output"
+      >
+        location.search=?foo=bar
+        searchParams=foo=bar
+        blocked=blocked
+      </pre>
+    `);
+  });
 });