diff --git a/apps/fabro-web/app/root.test.tsx b/apps/fabro-web/app/root.test.tsx
new file mode 100644
index 000000000..ab13a3457
--- /dev/null
+++ b/apps/fabro-web/app/root.test.tsx
@@ -0,0 +1,76 @@
+import { describe, expect, test } from "bun:test";
+import { renderToStaticMarkup } from "react-dom/server";
+import { createMemoryRouter, RouterProvider, type RouteObject } from "react-router";
+
+import { installRoutes } from "./install-router";
+import { routes } from "./router";
+
+async function renderPage(routeObjects: RouteObject[], path: string, navigate = false) {
+  const router = createMemoryRouter(routeObjects, {
+    initialEntries: [navigate ? "/" : path],
+  });
+  try {
+    if (navigate) await router.navigate(path);
+    return renderToStaticMarkup(<RouterProvider router={router} />);
+  } finally {
+    router.dispose();
+  }
+}
+
+describe("root error boundary", () => {
+  for (const path of ["/some_random_route", "/runs/existing-run/billing"]) {
+    for (const navigate of [false, true]) {
+      test(`${path} displays 404 on ${navigate ? "navigation" : "initial load"}`, async () => {
+        const html = await renderPage(routes, path, navigate);
+
+        expect(html).toContain(">404</p>");
+        expect(html).toContain("Page not found");
+        expect(html).not.toContain("Something went wrong");
+        expect(html).toContain('href="/runs"');
+        expect(html).toContain("Go back");
+      });
+    }
+  }
+
+  for (const [name, root] of [["app", routes[0]], ["installer", installRoutes[0]]] as const) {
+    async function renderFailure(error: unknown) {
+      return renderPage([
+        {
+          ...root,
+          children: [{
+            path: "failure",
+            loader() { throw error; },
+            Component: () => null,
+          }],
+        },
+      ], "/failure", true);
+    }
+
+    test(`${name} displays a route's 404 response as page not found`, async () => {
+      const html = await renderFailure(new Response(null, { status: 404 }));
+
+      expect(html).toContain(">404</p>");
+      expect(html).toContain("Page not found");
+      expect(html).not.toContain("Something went wrong");
+    });
+
+    test.each([403, 500])(`${name} preserves a route's %i error response`, async (status) => {
+      const statusText = status === 403 ? "Forbidden" : "Internal Server Error";
+      const html = await renderFailure(new Response(null, { status, statusText }));
+
+      expect(html).toContain(`>${status}</p>`);
+      expect(html).toContain(`${status} Error`);
+      expect(html).toContain(statusText);
+      expect(html).not.toContain("Page not found");
+    });
+
+    test(`${name} keeps unexpected exceptions as 500 errors`, async () => {
+      const html = await renderFailure(new Error("Unexpected route failure"));
+
+      expect(html).toContain(">500</p>");
+      expect(html).toContain("Something went wrong");
+      expect(html).toContain("Unexpected route failure");
+      expect(html).not.toContain("Page not found");
+    });
+  }
+});
diff --git a/apps/fabro-web/app/root.tsx b/apps/fabro-web/app/root.tsx
index 063d3579d..3ae5d252e 100644
--- a/apps/fabro-web/app/root.tsx
+++ b/apps/fabro-web/app/root.tsx
@@ -1,10 +1,11 @@
-import { isRouteErrorResponse, Outlet } from "react-router";
+import { isRouteErrorResponse, Outlet, useRouteError } from "react-router";
 
 export default function Root() {
   return <Outlet />;
 }
 
-export function ErrorBoundary({ error }: any) {
+export function ErrorBoundary() {
+  const error = useRouteError();
   let status = 500;
   let heading = "Something went wrong";
   let message = "An unexpected error occurred. Please try again.";