diff --git a/packages/react-router/tests/link.test.tsx b/packages/react-router/tests/link.test.tsx
index 4a8b15a959..fab45d8f0f 100644
--- a/packages/react-router/tests/link.test.tsx
+++ b/packages/react-router/tests/link.test.tsx
@@ -1184,6 +1184,55 @@ describe('Link', () => {
     expect(onError).toHaveBeenCalledOnce()
   })
 
+  test('when navigating to /posts with a beforeLoad that throws an primitive type error', async () => {
+    const onError = vi.fn()
+    const rootRoute = createRootRoute()
+    const indexRoute = createRoute({
+      getParentRoute: () => rootRoute,
+      path: '/',
+      component: () => {
+        return (
+          <>
+            <h1>Index</h1>
+            <Link to="/posts">Posts</Link>
+          </>
+        )
+      },
+    })
+
+    const PostsComponent = () => {
+      return <h1>Posts</h1>
+    }
+
+    const postsRoute = createRoute({
+      getParentRoute: () => rootRoute,
+      path: 'posts',
+      beforeLoad: () => {
+        throw 'This is a string error'
+      },
+      onError,
+      errorComponent: () => <span>Oops! Something went wrong!</span>,
+      component: PostsComponent,
+    })
+
+    const router = createRouter({
+      context: { userId: 'userId' },
+      routeTree: rootRoute.addChildren([indexRoute, postsRoute]),
+      history,
+    })
+
+    render(<RouterProvider router={router} />)
+
+    const postsLink = await screen.findByRole('link', { name: 'Posts' })
+
+    await act(() => fireEvent.click(postsLink))
+
+    const errorText = await screen.findByText('Oops! Something went wrong!')
+    expect(errorText).toBeInTheDocument()
+
+    expect(onError).toHaveBeenCalledOnce()
+  })
+
   test('when navigating to /posts with a beforeLoad that throws an error bubbles to the root', async () => {
     const rootRoute = createRootRoute({
       errorComponent: () => <span>Oops! Something went wrong!</span>,
diff --git a/packages/router-core/src/route.ts b/packages/router-core/src/route.ts
index 5d01b977f0..63efff3905 100644
--- a/packages/router-core/src/route.ts
+++ b/packages/router-core/src/route.ts
@@ -15,7 +15,7 @@ import type {
 } from './Matches'
 import type { RootRouteId } from './root'
 import type { ParseRoute, RouteById, RoutePaths } from './routeInfo'
-import type { AnyRouter, RegisteredRouter } from './router'
+import type { AnyRouter, RegisteredRouter, RouterCode } from './router'
 import type { BuildLocationFn, NavigateFn } from './RouterProvider'
 import type {
   Assign,
@@ -1072,7 +1072,7 @@ export interface UpdatableRouteOptions<
     SearchFilter<ResolveFullSearchSchema<TParentRoute, TSearchValidator>>
   >
   onCatch?: (error: Error) => void
-  onError?: (err: any) => void
+  onError?: (err: any, routerCode?: RouterCode) => void
   // These functions are called as route matches are loaded, stick around and leave the active
   // matches
   onEnter?: (
diff --git a/packages/router-core/src/router.ts b/packages/router-core/src/router.ts
index 30cb77f74a..8c28e967e2 100644
--- a/packages/router-core/src/router.ts
+++ b/packages/router-core/src/router.ts
@@ -679,6 +679,8 @@ export type AnyRouterWithContext<TContext> = RouterCore<
 
 export type AnyRouter = RouterCore<any, any, any, any, any>
 
+export type RouterCode = 'BEFORE_LOAD' | 'PARSE_PARAMS' | 'VALIDATE_SEARCH'
+
 export interface ViewTransitionOptions {
   types:
     | Array<string>
@@ -2106,7 +2108,11 @@ export class RouterCore<
       triggerOnReady()
     }
 
-    const handleRedirectAndNotFound = (match: AnyRouteMatch, err: any) => {
+    const handleRedirectAndNotFound = (
+      match: AnyRouteMatch,
+      err: any,
+      routerCode?: RouterCode,
+    ) => {
       if (isRedirect(err) || isNotFound(err)) {
         if (isRedirect(err)) {
           if (err.redirectHandled) {
@@ -2145,7 +2151,7 @@ export class RouterCore<
           err = this.resolveRedirect(err)
           throw err
         } else if (isNotFound(err)) {
-          this._handleNotFound(matches, err, {
+          this._handleNotFound(matches, err, routerCode, {
             updateMatch,
           })
           throw err
@@ -2175,7 +2181,7 @@ export class RouterCore<
             const handleSerialError = (
               index: number,
               err: any,
-              routerCode: string,
+              routerCode: RouterCode,
             ) => {
               const { id: matchId, routeId } = matches[index]!
               const route = this.looseRoutesById[routeId]!
@@ -2187,15 +2193,22 @@ export class RouterCore<
                 throw err
               }
 
-              err.routerCode = routerCode
               firstBadMatchIndex = firstBadMatchIndex ?? index
-              handleRedirectAndNotFound(this.getMatch(matchId)!, err)
+              handleRedirectAndNotFound(
+                this.getMatch(matchId)!,
+                err,
+                routerCode,
+              )
 
               try {
-                route.options.onError?.(err)
+                route.options.onError?.(err, routerCode)
               } catch (errorHandlerErr) {
                 err = errorHandlerErr
-                handleRedirectAndNotFound(this.getMatch(matchId)!, err)
+                handleRedirectAndNotFound(
+                  this.getMatch(matchId)!,
+                  err,
+                  routerCode,
+                )
               }
 
               updateMatch(matchId, (prev) => {
@@ -3019,6 +3032,7 @@ export class RouterCore<
   _handleNotFound = (
     matches: Array<AnyRouteMatch>,
     err: NotFoundError,
+    routerCode?: string,
     {
       updateMatch = this.updateMatch,
     }: {
@@ -3069,10 +3083,9 @@ export class RouterCore<
       error: err,
       isFetching: false,
     }))
-
-    if ((err as any).routerCode === 'BEFORE_LOAD' && routeCursor.parentRoute) {
+    if (routerCode === 'BEFORE_LOAD' && routeCursor.parentRoute) {
       err.routeId = routeCursor.parentRoute.id
-      this._handleNotFound(matches, err, {
+      this._handleNotFound(matches, err, routerCode, {
         updateMatch,
       })
     }