Solving the "Element type is invalid" Error in Next.js: A Tale of Two Imports

Recently, I ran into an error that seemed to defy logic:

Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined.

Check the render method of `Page`.

The strange part? A component would work perfectly on one page but crash the app when used in another, even though the import and usage looked identical. After a deep dive, the culprit was found, and it's a subtle but crucial detail about how we import our components.

This is the story of that bug and the best practice that will prevent it from ever happening to you again.

The Scene of the Crime

Let's set up the players. We have a few components:

The following code omits many details, and some parts are not typed, just to roughly illustrate and explain this error.

The File Structure

All reusable components are neatly organized in a components directory.

/
├── app/
│   └── [locale]/
│       └── page.tsx          // The Homepage, Server component
└── components/
    ├── ToolCard.tsx          // Our Client Component
    └── layout/
        ├── tool-layout.tsx     // Server Component layout
        └── tool-recommend.tsx  // Server Component that uses ToolCard

**Import chain: **

• page.tsx(server) -> ToolCard.tsx(client)
• tool-layout.tsx(server) -> tool-recommend.tsx(server) -> ToolCard.tsx(client)

1. ToolCard.tsx

A simple, reusable presentation component. Crucially, it's a Client Component because it uses the useTheme hook.

// /components/ToolCard.tsx
"use client";

import Image from 'next/image';
import { useTheme } from 'next-themes';

export default function ToolCard({ href, imgSrc, imgAlt, title }) {
    const { resolvedTheme } = useTheme();
    // ... component logic
    return (
        <a href={href}>
            {/* ... */}
            <Image src={imgSrc} alt={imgAlt} className={resolvedTheme === 'dark' ? "invert" : ""} />
            <div>{title}</div>
        </a>
    );
};

2. ToolRecommend.tsx

A Server Component that fetches some data and uses ToolCard to display recommended tools.

I used to display recommended tools using <a> elements, but today I decided to replace them with the <ToolCard> component I used on the home page. However, the app crashed. The strangest part is that I even copied the absolute import (import ToolCard from '@/components/ToolCard';) directly from the home page's TSX file, and the usage is exactly the same.

// /components/layout/tool-recommend.tsx
import siteData from "@/app/siteData";
import { getI18n } from "@/locales/server";
import ToolCard from '@/components/ToolCard'; // <-- Absolute import!

export default async function ToolRecommend({ toolname, locale }) {
    const t = await getI18n();
    // ... logic to get recommended tools
    return (
        <div>
            <h2>{t("global.recommend")}</h2>
            <div className="flex flex-wrap gap-1">
                {/* It uses the client component */}
                <ToolCard href="/" imgSrc="/icon.png" imgAlt="Test" title="Test Card" />
                {/* ... other recommended tools */}
            </div>
        </div>
    );
}

The Mystery: Works Here, Fails There

On my homepage (/app/[locale]/page.tsx), I was using ToolCard directly(import ToolCard from '@/components/ToolCard';). Everything worked perfectly.

Then, I created a layout for my tool pages, tool-layout.tsx. This layout would, in turn, render the ToolRecommend component.

Here is the code for /components/layout/tool-layout.tsx:

// /components/layout/tool-layout.tsx

// The problem is hidden in this line!
import ToolRecommend from "./tool-recommend"; 
import { getI18n } from "@/locales/server";

export default async function ToolLayout({ children, toolname, lang }) {
    const t = await getI18n();

    return (
        <div>
            {children}
            {/* The component that crashes the app */}
            <ToolRecommend toolname={toolname} locale={lang} />
            {/* ... other layout elements */}
        </div>
    );
}

When I navigated to a tool page that used this layout, the app crashed with the Element type is invalid... but got: undefined error, pointing to ToolRecommend.tsx.

The puzzle was: Why does ToolCard resolve correctly on the homepage but become undefined inside ToolRecommend when it's used by ToolLayout? I checked the exports, the file names, everything. It made no sense.

Relative vs. Absolute Imports

The answer was not in the component's code, but in a single character in the import statement inside tool-layout.tsx:

The failing import (relative path):

import ToolRecommend from "./tool-recommend";

The . tells the bundler to look for the file in the same directory.

The fix (absolute path alias):

import ToolRecommend from "@/components/layout/tool-recommend";

The @/ is a path alias (configured in tsconfig.json or jsconfig.json) that points to the project's root. This gives the bundler an unambiguous, absolute path to the module.

Why does this matter so much?

The Next.js App Router's bundler builds a complex dependency graph that carefully separates Server and Client modules.

• When you use an absolute path (@/components/...), you give the bundler a clear, stable "address" for the module. It can reliably analyze the file, identify it as a Server Component, and correctly resolve its dependencies (like the client component ToolCard).

• When you use a relative path (./...), especially in a chain of Server-to-Server component imports (ToolLayout -> ToolRecommend), you create a context-dependent path. It seems that in this specific scenario, the Next.js bundler gets confused. It struggles to maintain the correct context for the nested component (ToolRecommend) and fails to resolve its own dependency (ToolCard), causing it to be undefined.

Best Practice

To avoid this headache and write more robust, maintainable Next.js applications, adopt this simple rule:

Always prefer absolute path aliases (@/) over relative paths (./, ../) for importing components within your Next.js App Router project.

Benefits of this approach:

1. Avoids Subtle Bugs: It prevents confusing bundling errors like the one described here.
2. Improves Readability: Imports are consistent and clear, no matter how deeply nested your files are.
3. Simplifies Refactoring: If you move a file, you don't have to go back and fix a chain of ../.. relative imports. You only change the imports within the moved file itself.

Happy coding