Error map
Failed prop type: The prop href expects a string or object in <Link> Next.js: Error: Failed prop type: The prop `href` expects a `string` or `object` in `<Link>`, but got `undefined` instead
Next.js · layer 1, On your device
Centre: this error. First ring: errors it is linked with (12). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (12)
Warning: `key` is not a prop. Trying to access it will result in `undefined` being returned.
A component tried to read props.key, which React reserves and never passes down.
Warning: Received `true` for a non-boolean attribute `x`.
A boolean was passed to a DOM attribute that expects a string, or a custom prop leaked through to a DOM element.
You're importing a component that needs useState. It only works in a Client Component but none of its parents are marked with "use client"
In the Next.js App Router, a component using hooks or browser APIs is rendered as a Server Component.
Next.js: ⨯ Conflicting app and page file was found, please remove the conflicting files to continue: "pages/index.tsx" - "app/page.tsx"
The same URL is defined in both the `app` and `pages` directories.
Browser: Access to fetch at 'https://api.example.com/api/data' from origin 'https://app.example.com' has been blocked by CORS policy (Next.js route handler)
A cross-origin request to your Next.js API route is blocked because the response lacks CORS headers.
TypeScript: error TS2741: Property 'email' is missing in type '{ name: string; }' but required in type 'User'.
An object lacks one required property of the target type.
Vue: [Vue warn]: Missing required prop: "title"
A component marked a prop as `required` but the parent didn't pass it.
Vue: [Vue warn]: Set operation on key "name" failed: target is readonly.
You mutated a readonly reactive object (props, `readonly()`, `shallowReadonly`, or a frozen/store state).
Next.js: FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory (during next build)
Node ran out of memory while building a large Next.js app (or on a small CI/Vercel runner).
Next.js: Error occurred prerendering page "/blog" TypeError: fetch failed { cause: Error: connect ECONNREFUSED 127.0.0.1:3000 }
During `next build` a page tried to fetch data from a server (often your own app or an API) that isn't running yet.
Next.js 13+: Error: Invalid <Link> with <a> child. Please remove <a> or use <Link legacyBehavior>
Since Next.js 13 `` renders its own ``, so nesting your own `` is invalid.
Next.js: You have a Server Component that imports next/router. Use next/navigation instead
`next/router` (Pages Router) was imported in an App Router component.
Two steps away (33)
Warning: Each child in a list should have a unique "key" prop
When rendering a list with `.map()`, each element needs a stable, unique `key` so React can track items between renders.
Warning: A component is changing an uncontrolled input to be controlled
An input’s `value` started as `undefined` (uncontrolled) and later became a defined value (controlled), or vice versa.
IndexError: list index out of range
Code accessed a list position that doesn’t exist.
Error: Objects are not valid as a React child
You tried to render a plain object (or a Promise/Date) directly in JSX; React can only render strings, numbers, elements and arra…
Error: Nothing was returned from render. This usually means a return statement is missing.
A component returned undefined (React 17 and earlier) — usually a missing return or a return followed by a line break.
Adjacent JSX elements must be wrapped in an enclosing tag. Did you want a JSX fragment <>...</>?
A component returns two sibling JSX elements without a single parent.
Error: Hydration failed because the initial UI does not match what was rendered on the server
The HTML rendered on the server differs from the first client render, so React (Next.js/Remix) can’t attach to it.
Module not found: Can't resolve 'fs' (Next.js / webpack 5)
A Node.js built-in (fs, path, crypto, net) is imported into code that runs in the browser bundle.
Error: Dynamic server usage: Route /x couldn't be rendered statically because it used `cookies`
Next.js tried to statically render a route that reads request-specific data (cookies, headers, searchParams).
TypeError: Missing parameter name at 1 (path-to-regexp)
An Express 5 (path-to-regexp v8) route uses old wildcard syntax like '*' or '/:id?'.
No routes matched location "/x"
React Router found no route definition for the current URL.
Error occurred prerendering page "/x". Read more: https://nextjs.org/docs/messages/prerender-error
A page threw an error while Next.js was rendering it at build time.
Browser: Access to XMLHttpRequest at 'https://api.example.com' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header — Laravel
The browser blocked a cross-origin call to your Laravel API because the response lacks the right CORS headers.
Next.js: Warning: validateDOMNesting(...): <div> cannot appear as a descendant of <p> / In HTML, <p> cannot be a descendant of <p>. This will cause a hydration error
The rendered HTML has an invalid element nesting, so the browser "fixes" it and React's hydration no longer matches.
Next.js: You're importing a component that needs createContext. It only works in a Client Component but none of its parents are marked with "use client"
A context provider (or a lib that uses `createContext`) is used in a Server Component.
TS2339: Property 'x' does not exist on type 'Y'.
TypeScript’s type for the object doesn’t include that property.
Vue: [Vue warn]: Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders
A child component assigned to a prop. Props flow one way — the parent owns the value.
TypeScript: error TS2551: Property 'lenght' does not exist on type 'string'. Did you mean 'length'?
A property name is misspelled (TypeScript suggests the closest valid one).
Vue: [Vue warn]: Property "x" was accessed during render but is not defined on instance
The template references a variable/function that the component doesn’t expose.
TypeScript: error TS7031: Binding element 'name' implicitly has an 'any' type.
A destructured parameter has no type, so its elements default to `any`.
Vue: [Vue warn]: Extraneous non-props attributes (class) were passed to component but could not be automatically inherited because component renders fragment or text root nodes
Attributes (class, style, listeners) passed to a component can't be applied because the component has multiple root nodes.
Vue: [Vue warn]: Invalid prop: type check failed for prop "count". Expected Number with value 5, got String with value "5"
A prop received a value of the wrong type.
Vue: [Vue warn]: Maximum recursive updates exceeded in component <Foo>. This means you have a reactive effect that is mutating its own dependencies and thus recursively triggering itself
A watcher/computed/render effect keeps changing the state it depends on, creating an infinite update loop.
Vue: [Vue warn]: Write operation failed: computed value is readonly
You assigned to a `computed` that has no setter.
npm ERR! code ELIFECYCLE / Command failed with exit code 1
An npm script (build, start, test, postinstall) exited with an error. ELIFECYCLE is only the wrapper — the real error is printed…
gyp ERR! build error / node-gyp rebuild failed
A dependency with native C/C++ code couldn’t compile — missing build tools, Python, or an unsupported Node version.
FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory
The V8 heap hit its limit — a large build (webpack, tsc, Next.js) needs more memory, or the app leaks.
Error: error:0308010C:digital envelope routines::unsupported
An old build tool (webpack 4, old react-scripts) uses a hash algorithm that OpenSSL 3 in Node 17+ disables.
Error: @prisma/client did not initialize yet. Please run "prisma generate"
The generated Prisma Client is missing or out of date.
Error: Node Sass does not yet support your current environment
node-sass (deprecated) has no binary for your Node version/OS.
Error: NextRouter was not mounted.
next/router’s useRouter was used inside the App Router (app/ directory), which uses next/navigation instead.
Next.js: Error: No HTTP methods exported in '/app/api/users/route.ts'. Export a named export for each HTTP method (GET, POST...)
A Route Handler file exports no recognised HTTP method function.
Next.js: You are attempting to export "metadata" from a component marked with "use client", which is disallowed
`metadata`/`generateMetadata` can only be exported from Server Components.
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