diff --git a/sentry-javascript/19580/.react-router/types/+future.ts b/sentry-javascript/19580/.react-router/types/+future.ts
new file mode 100644
index 0000000..7f4533c
--- /dev/null
+++ b/sentry-javascript/19580/.react-router/types/+future.ts
@@ -0,0 +1,9 @@
+// Generated by React Router
+
+import "react-router";
+
+declare module "react-router" {
+  interface Future {
+    v8_middleware: false
+  }
+}
\ No newline at end of file
diff --git a/sentry-javascript/19580/.react-router/types/+routes.ts b/sentry-javascript/19580/.react-router/types/+routes.ts
new file mode 100644
index 0000000..4566862
--- /dev/null
+++ b/sentry-javascript/19580/.react-router/types/+routes.ts
@@ -0,0 +1,43 @@
+// Generated by React Router
+
+import "react-router"
+
+declare module "react-router" {
+  interface Register {
+    pages: Pages
+    routeFiles: RouteFiles
+    routeModules: RouteModules
+  }
+}
+
+type Pages = {
+  "/": {
+    params: {};
+  };
+  "/items/:id": {
+    params: {
+      "id": string;
+    };
+  };
+};
+
+type RouteFiles = {
+  "root.tsx": {
+    id: "root";
+    page: "/" | "/items/:id";
+  };
+  "routes/home.tsx": {
+    id: "routes/home";
+    page: "/";
+  };
+  "routes/items.$id.tsx": {
+    id: "routes/items.$id";
+    page: "/items/:id";
+  };
+};
+
+type RouteModules = {
+  "root": typeof import("./app/root.tsx");
+  "routes/home": typeof import("./app/routes/home.tsx");
+  "routes/items.$id": typeof import("./app/routes/items.$id.tsx");
+};
\ No newline at end of file
diff --git a/sentry-javascript/19580/.react-router/types/+server-build.d.ts b/sentry-javascript/19580/.react-router/types/+server-build.d.ts
new file mode 100644
index 0000000..13792c1
--- /dev/null
+++ b/sentry-javascript/19580/.react-router/types/+server-build.d.ts
@@ -0,0 +1,18 @@
+// Generated by React Router
+
+declare module "virtual:react-router/server-build" {
+  import { ServerBuild } from "react-router";
+  export const assets: ServerBuild["assets"];
+  export const assetsBuildDirectory: ServerBuild["assetsBuildDirectory"];
+  export const basename: ServerBuild["basename"];
+  export const entry: ServerBuild["entry"];
+  export const future: ServerBuild["future"];
+  export const isSpaMode: ServerBuild["isSpaMode"];
+  export const prerender: ServerBuild["prerender"];
+  export const publicPath: ServerBuild["publicPath"];
+  export const routeDiscovery: ServerBuild["routeDiscovery"];
+  export const routes: ServerBuild["routes"];
+  export const ssr: ServerBuild["ssr"];
+  export const allowedActionOrigins: ServerBuild["allowedActionOrigins"];
+  export const unstable_getCriticalCss: ServerBuild["unstable_getCriticalCss"];
+}
\ No newline at end of file
diff --git a/sentry-javascript/19580/.react-router/types/app/+types/root.ts b/sentry-javascript/19580/.react-router/types/app/+types/root.ts
new file mode 100644
index 0000000..5bd414e
--- /dev/null
+++ b/sentry-javascript/19580/.react-router/types/app/+types/root.ts
@@ -0,0 +1,59 @@
+// Generated by React Router
+
+import type { GetInfo, GetAnnotations } from "react-router/internal";
+
+type Module = typeof import("../root.js")
+
+type Info = GetInfo<{
+  file: "root.tsx",
+  module: Module
+}>
+
+type Matches = [{
+  id: "root";
+  module: typeof import("../root.js");
+}];
+
+type Annotations = GetAnnotations<Info & { module: Module, matches: Matches }, false>;
+
+export namespace Route {
+  // links
+  export type LinkDescriptors = Annotations["LinkDescriptors"];
+  export type LinksFunction = Annotations["LinksFunction"];
+
+  // meta
+  export type MetaArgs = Annotations["MetaArgs"];
+  export type MetaDescriptors = Annotations["MetaDescriptors"];
+  export type MetaFunction = Annotations["MetaFunction"];
+
+  // headers
+  export type HeadersArgs = Annotations["HeadersArgs"];
+  export type HeadersFunction = Annotations["HeadersFunction"];
+
+  // middleware
+  export type MiddlewareFunction = Annotations["MiddlewareFunction"];
+
+  // clientMiddleware
+  export type ClientMiddlewareFunction = Annotations["ClientMiddlewareFunction"];
+
+  // loader
+  export type LoaderArgs = Annotations["LoaderArgs"];
+
+  // clientLoader
+  export type ClientLoaderArgs = Annotations["ClientLoaderArgs"];
+
+  // action
+  export type ActionArgs = Annotations["ActionArgs"];
+
+  // clientAction
+  export type ClientActionArgs = Annotations["ClientActionArgs"];
+
+  // HydrateFallback
+  export type HydrateFallbackProps = Annotations["HydrateFallbackProps"];
+
+  // Component
+  export type ComponentProps = Annotations["ComponentProps"];
+
+  // ErrorBoundary
+  export type ErrorBoundaryProps = Annotations["ErrorBoundaryProps"];
+}
\ No newline at end of file
diff --git a/sentry-javascript/19580/.react-router/types/app/routes/+types/home.ts b/sentry-javascript/19580/.react-router/types/app/routes/+types/home.ts
new file mode 100644
index 0000000..e49d62a
--- /dev/null
+++ b/sentry-javascript/19580/.react-router/types/app/routes/+types/home.ts
@@ -0,0 +1,62 @@
+// Generated by React Router
+
+import type { GetInfo, GetAnnotations } from "react-router/internal";
+
+type Module = typeof import("../home.js")
+
+type Info = GetInfo<{
+  file: "routes/home.tsx",
+  module: Module
+}>
+
+type Matches = [{
+  id: "root";
+  module: typeof import("../../root.js");
+}, {
+  id: "routes/home";
+  module: typeof import("../home.js");
+}];
+
+type Annotations = GetAnnotations<Info & { module: Module, matches: Matches }, false>;
+
+export namespace Route {
+  // links
+  export type LinkDescriptors = Annotations["LinkDescriptors"];
+  export type LinksFunction = Annotations["LinksFunction"];
+
+  // meta
+  export type MetaArgs = Annotations["MetaArgs"];
+  export type MetaDescriptors = Annotations["MetaDescriptors"];
+  export type MetaFunction = Annotations["MetaFunction"];
+
+  // headers
+  export type HeadersArgs = Annotations["HeadersArgs"];
+  export type HeadersFunction = Annotations["HeadersFunction"];
+
+  // middleware
+  export type MiddlewareFunction = Annotations["MiddlewareFunction"];
+
+  // clientMiddleware
+  export type ClientMiddlewareFunction = Annotations["ClientMiddlewareFunction"];
+
+  // loader
+  export type LoaderArgs = Annotations["LoaderArgs"];
+
+  // clientLoader
+  export type ClientLoaderArgs = Annotations["ClientLoaderArgs"];
+
+  // action
+  export type ActionArgs = Annotations["ActionArgs"];
+
+  // clientAction
+  export type ClientActionArgs = Annotations["ClientActionArgs"];
+
+  // HydrateFallback
+  export type HydrateFallbackProps = Annotations["HydrateFallbackProps"];
+
+  // Component
+  export type ComponentProps = Annotations["ComponentProps"];
+
+  // ErrorBoundary
+  export type ErrorBoundaryProps = Annotations["ErrorBoundaryProps"];
+}
\ No newline at end of file
diff --git a/sentry-javascript/19580/.react-router/types/app/routes/+types/items.$id.ts b/sentry-javascript/19580/.react-router/types/app/routes/+types/items.$id.ts
new file mode 100644
index 0000000..15d74b3
--- /dev/null
+++ b/sentry-javascript/19580/.react-router/types/app/routes/+types/items.$id.ts
@@ -0,0 +1,62 @@
+// Generated by React Router
+
+import type { GetInfo, GetAnnotations } from "react-router/internal";
+
+type Module = typeof import("../items.$id.js")
+
+type Info = GetInfo<{
+  file: "routes/items.$id.tsx",
+  module: Module
+}>
+
+type Matches = [{
+  id: "root";
+  module: typeof import("../../root.js");
+}, {
+  id: "routes/items.$id";
+  module: typeof import("../items.$id.js");
+}];
+
+type Annotations = GetAnnotations<Info & { module: Module, matches: Matches }, false>;
+
+export namespace Route {
+  // links
+  export type LinkDescriptors = Annotations["LinkDescriptors"];
+  export type LinksFunction = Annotations["LinksFunction"];
+
+  // meta
+  export type MetaArgs = Annotations["MetaArgs"];
+  export type MetaDescriptors = Annotations["MetaDescriptors"];
+  export type MetaFunction = Annotations["MetaFunction"];
+
+  // headers
+  export type HeadersArgs = Annotations["HeadersArgs"];
+  export type HeadersFunction = Annotations["HeadersFunction"];
+
+  // middleware
+  export type MiddlewareFunction = Annotations["MiddlewareFunction"];
+
+  // clientMiddleware
+  export type ClientMiddlewareFunction = Annotations["ClientMiddlewareFunction"];
+
+  // loader
+  export type LoaderArgs = Annotations["LoaderArgs"];
+
+  // clientLoader
+  export type ClientLoaderArgs = Annotations["ClientLoaderArgs"];
+
+  // action
+  export type ActionArgs = Annotations["ActionArgs"];
+
+  // clientAction
+  export type ClientActionArgs = Annotations["ClientActionArgs"];
+
+  // HydrateFallback
+  export type HydrateFallbackProps = Annotations["HydrateFallbackProps"];
+
+  // Component
+  export type ComponentProps = Annotations["ComponentProps"];
+
+  // ErrorBoundary
+  export type ErrorBoundaryProps = Annotations["ErrorBoundaryProps"];
+}
\ No newline at end of file
diff --git a/sentry-javascript/19580/README.md b/sentry-javascript/19580/README.md
new file mode 100644
index 0000000..8ae19e3
--- /dev/null
+++ b/sentry-javascript/19580/README.md
@@ -0,0 +1,52 @@
+# Reproduction for sentry-javascript#19580
+
+**Issue:** https://github.com/getsentry/sentry-javascript/issues/19580
+
+## Description
+
+`reactRouterTracingIntegration` produces `[object Object]` as transaction name when navigating using a `<Link>` (or `navigate()`) with an object `to` prop, e.g.:
+
+```tsx
+<Link to={{ pathname: "/items/2", search: "redirectTo=%2F" }}>
+```
+
+The root cause is in the patched `navigate` function which uses `String(args[0])` to derive the transaction name. When called with an object, `String({...})` produces `"[object Object]"`.
+
+## Steps to Reproduce
+
+1. Set your Sentry DSN:
+   ```bash
+   export SENTRY_DSN=<your-dsn>
+   ```
+
+2. Install dependencies:
+   ```bash
+   npm install
+   ```
+
+3. Start the dev server:
+   ```bash
+   npm run dev
+   ```
+
+4. Open the app in your browser (http://localhost:5173)
+
+5. Click **"Link with object to={{ pathname: "/items/2", search: "..." }}"** — this navigates using an object `to` prop
+
+6. Check Sentry: the transaction name for this navigation will be `[object Object]`
+
+7. For comparison, click **"Link with string to="/items/1?redirectTo=%2F""** — this navigates using a string `to` prop and the transaction name is correct
+
+## Expected Behavior
+
+Transaction name should be the resolved pathname (e.g., `/items/2`), not `[object Object]`.
+
+## Actual Behavior
+
+Transaction name is `[object Object]` when navigating with an object `to` prop.
+
+## Environment
+
+- `@sentry/react-router`: ^9.38.0
+- React Router: v7 (framework mode)
+- React: 19
diff --git a/sentry-javascript/19580/app/entry.client.tsx b/sentry-javascript/19580/app/entry.client.tsx
new file mode 100644
index 0000000..f6720f9
--- /dev/null
+++ b/sentry-javascript/19580/app/entry.client.tsx
@@ -0,0 +1,34 @@
+import * as Sentry from "@sentry/react-router";
+import { startTransition, StrictMode } from "react";
+import { hydrateRoot } from "react-dom/client";
+import { HydratedRouter } from "react-router/dom";
+
+if (process.env.SENTRY_DSN) {
+  console.log("SENTRY_DSN is set, initializing Sentry");
+} else {
+  console.log("SENTRY_DSN is not set, skipping Sentry initialization");
+}
+
+Sentry.init({
+  dsn: process.env.SENTRY_DSN || "",
+  integrations: [Sentry.reactRouterTracingIntegration()],
+  tracesSampleRate: 1.0,
+  debug: true,
+  beforeSendTransaction(event) {
+    const name = event.transaction;
+    console.log(
+      `[Sentry Transaction] name: "${name}", source: "${event.transaction_info?.source}"`,
+      name === "[object Object]" ? " <-- BUG (issue #19580)" : ""
+    );
+    return event;
+  },
+});
+
+startTransition(() => {
+  hydrateRoot(
+    document,
+    <StrictMode>
+      <HydratedRouter />
+    </StrictMode>
+  );
+});
diff --git a/sentry-javascript/19580/app/entry.server.tsx b/sentry-javascript/19580/app/entry.server.tsx
new file mode 100644
index 0000000..a73718b
--- /dev/null
+++ b/sentry-javascript/19580/app/entry.server.tsx
@@ -0,0 +1,14 @@
+import * as Sentry from "@sentry/react-router";
+import { renderToPipeableStream } from "react-dom/server";
+import { ServerRouter } from "react-router";
+import { createReadableStreamFromReadable } from "@react-router/node";
+
+export default Sentry.createSentryHandleRequest({
+  ServerRouter,
+  renderToPipeableStream,
+  createReadableStreamFromReadable,
+});
+
+export const handleError = Sentry.createSentryHandleError({
+  logErrors: false,
+});
diff --git a/sentry-javascript/19580/app/root.tsx b/sentry-javascript/19580/app/root.tsx
new file mode 100644
index 0000000..11d5972
--- /dev/null
+++ b/sentry-javascript/19580/app/root.tsx
@@ -0,0 +1,23 @@
+import { Links, Meta, Outlet, Scripts, ScrollRestoration } from "react-router";
+
+export function Layout({ children }: { children: React.ReactNode }) {
+  return (
+    <html lang="en">
+      <head>
+        <meta charSet="utf-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1" />
+        <Meta />
+        <Links />
+      </head>
+      <body>
+        {children}
+        <ScrollRestoration />
+        <Scripts />
+      </body>
+    </html>
+  );
+}
+
+export default function App() {
+  return <Outlet />;
+}
diff --git a/sentry-javascript/19580/app/routes.ts b/sentry-javascript/19580/app/routes.ts
new file mode 100644
index 0000000..d55ed6c
--- /dev/null
+++ b/sentry-javascript/19580/app/routes.ts
@@ -0,0 +1,6 @@
+import { type RouteConfig, index, route } from "@react-router/dev/routes";
+
+export default [
+  index("routes/home.tsx"),
+  route("items/:id", "routes/items.$id.tsx"),
+] satisfies RouteConfig;
diff --git a/sentry-javascript/19580/app/routes/home.tsx b/sentry-javascript/19580/app/routes/home.tsx
new file mode 100644
index 0000000..ab27756
--- /dev/null
+++ b/sentry-javascript/19580/app/routes/home.tsx
@@ -0,0 +1,59 @@
+import { Link, useNavigate } from "react-router";
+
+export default function Home() {
+  const navigate = useNavigate();
+
+  return (
+    <div style={{ padding: "2rem", fontFamily: "sans-serif" }}>
+      <h1>Reproduction: sentry-javascript#19580</h1>
+      <p>
+        <code>reactRouterTracingIntegration</code> uses <code>String(args[0])</code> for
+        the transaction name. When <code>navigate(to)</code> is called with an object{" "}
+        <code>to</code>, that becomes <code>[object Object]</code>.
+      </p>
+      <p>
+        <strong>Open the browser console</strong> and look for{" "}
+        <code>[Sentry Transaction] name: "..."</code> — when you navigate with an
+        object, the name should be <code>[object Object]</code> (the bug).
+      </p>
+
+      <h2>1. Navigate with string (correct name)</h2>
+      <p>
+        <Link to="/items/1?redirectTo=%2F">
+          Link with string <code>to="/items/1?redirectTo=%2F"</code>
+        </Link>
+      </p>
+
+      <h2>2. Navigate with object – Link (bug)</h2>
+      <p>
+        <Link
+          to={{
+            pathname: "/items/2",
+            search: `redirectTo=${encodeURIComponent("/")}`,
+          }}
+        >
+          Link with object <code>to=&#123;&#123; pathname, search &#125;&#125;</code>
+        </Link>
+      </p>
+
+      <h2>3. Navigate with object – programmatic (bug; most reliable)</h2>
+      <p>
+        This calls <code>navigate(&#123; pathname, search &#125;)</code> directly, so
+        the router receives the object and Sentry does <code>String(args[0])</code>.
+      </p>
+      <p>
+        <button
+          type="button"
+          onClick={() =>
+            navigate({
+              pathname: "/items/3",
+              search: `redirectTo=${encodeURIComponent("/")}`,
+            })
+          }
+        >
+          navigate(&#123; pathname: "/items/3", search: "..." &#125;)
+        </button>
+      </p>
+    </div>
+  );
+}
diff --git a/sentry-javascript/19580/app/routes/items.$id.tsx b/sentry-javascript/19580/app/routes/items.$id.tsx
new file mode 100644
index 0000000..1abaa60
--- /dev/null
+++ b/sentry-javascript/19580/app/routes/items.$id.tsx
@@ -0,0 +1,17 @@
+import { Link, useParams, useSearchParams } from "react-router";
+
+export default function ItemDetail() {
+  const { id } = useParams();
+  const [searchParams] = useSearchParams();
+  const redirectTo = searchParams.get("redirectTo") || "/";
+
+  return (
+    <div style={{ padding: "2rem", fontFamily: "sans-serif" }}>
+      <h1>Item {id}</h1>
+      <p>redirectTo: {redirectTo}</p>
+      <p>
+        <Link to="/">Back to home</Link>
+      </p>
+    </div>
+  );
+}
diff --git a/sentry-javascript/19580/instrument.server.mjs b/sentry-javascript/19580/instrument.server.mjs
new file mode 100644
index 0000000..606715a
--- /dev/null
+++ b/sentry-javascript/19580/instrument.server.mjs
@@ -0,0 +1,13 @@
+import * as Sentry from "@sentry/react-router";
+
+if (process.env.SENTRY_DSN) {
+  console.log("SENTRY_DSN is set, initializing Sentry");
+} else {
+  console.log("SENTRY_DSN is not set, skipping Sentry initialization");
+}
+
+Sentry.init({
+  dsn: process.env.SENTRY_DSN || "",
+  tracesSampleRate: 1.0,
+  debug: false,
+});
diff --git a/sentry-javascript/19580/package.json b/sentry-javascript/19580/package.json
new file mode 100644
index 0000000..84cb2e2
--- /dev/null
+++ b/sentry-javascript/19580/package.json
@@ -0,0 +1,25 @@
+{
+  "name": "sentry-javascript-19580-repro",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "NODE_OPTIONS='--import ./instrument.server.mjs' NODE_ENV=production react-router dev",
+    "build": "NODE_ENV=production react-router build",
+    "start": "NODE_OPTIONS='--import ./instrument.server.mjs' NODE_ENV=production react-router-serve ./build/server/index.js"
+  },
+  "dependencies": {
+    "@sentry/react-router": "^9.38.0",
+    "react": "19.0.0",
+    "react-dom": "19.0.0",
+    "react-router": "^7.6.1",
+    "@react-router/node": "^7.6.1"
+  },
+  "devDependencies": {
+    "@react-router/dev": "^7.6.1",
+    "@react-router/serve": "^7.6.1",
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
+    "typescript": "^5.7.0",
+    "vite": "^6.0.0"
+  }
+}
diff --git a/sentry-javascript/19580/react-router.config.ts b/sentry-javascript/19580/react-router.config.ts
new file mode 100644
index 0000000..e45e273
--- /dev/null
+++ b/sentry-javascript/19580/react-router.config.ts
@@ -0,0 +1,5 @@
+import type { Config } from "@react-router/dev/config";
+
+export default {
+  ssr: true,
+} satisfies Config;
diff --git a/sentry-javascript/19580/tsconfig.json b/sentry-javascript/19580/tsconfig.json
new file mode 100644
index 0000000..71c227c
--- /dev/null
+++ b/sentry-javascript/19580/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "include": ["app/**/*.ts", "app/**/*.tsx", "vite.config.ts", "react-router.config.ts"],
+  "compilerOptions": {
+    "lib": ["DOM", "DOM.Iterable", "ES2022"],
+    "target": "ES2022",
+    "module": "ES2022",
+    "moduleResolution": "bundler",
+    "jsx": "react-jsx",
+    "strict": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "noEmit": true,
+    "types": ["vite/client"]
+  }
+}
diff --git a/sentry-javascript/19580/vite.config.ts b/sentry-javascript/19580/vite.config.ts
new file mode 100644
index 0000000..7ffae05
--- /dev/null
+++ b/sentry-javascript/19580/vite.config.ts
@@ -0,0 +1,6 @@
+import { reactRouter } from "@react-router/dev/vite";
+import { defineConfig } from "vite";
+
+export default defineConfig({
+  plugins: [reactRouter()],
+});