Error map
You cannot use different slug names for the same dynamic path Next.js: Error: You cannot use different slug names for the same dynamic path ('id' !== 'slug')
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)
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: NextRouter was not mounted.
next/router’s useRouter was used inside the App Router (app/ directory), which uses next/navigation instead.
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.
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.
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.
Next.js 15: Error: Route "/blog/[slug]" used `params.slug`. `params` should be awaited before using its properties
In Next.js 15 `params` and `searchParams` are Promises; reading properties synchronously triggers this error/warning.
Next.js: Page "/blog/[slug]" is missing "generateStaticParams()" so it cannot be used with "output: export" config
A dynamic route can't be statically exported without telling Next.js which paths to generate.
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.
Vue Router: [Vue Router warn]: No match found for location with path "/users/42"
The router has no route record matching that path (typo, missing route, or case/base issue).
Nuxt: 404 Page not found: /blog/my-post / [Vue Router warn]: No match found for location with path
Nuxt's file-based router has no page matching the URL (wrong file/folder names or missing param syntax).
Two steps away (36)
HTTP 404 Not Found
The server can’t find anything at the requested URL.
HTTP 405 Method Not Allowed
The URL exists, but it doesn’t accept the HTTP method you used (e.g. POST to a GET-only route).
Whitelabel Error Page — This application has no explicit mapping for /error
Spring Boot’s default error page — the request hit no controller mapping (404) or a controller threw (500).
Error: useNavigate() may be used only in the context of a <Router> component.
A React Router hook ran in a component that isn’t rendered inside a Router provider.
API Error: Cannot GET /api/... / No route matches / The route could not be found
The server has no route for this URL and HTTP method combination — the endpoint path, API version prefix or method is wrong.
connect: Network is unreachable (ENETUNREACH)
The host has no route to the destination network — no default gateway, interface down, or trying IPv6 without IPv6 connectivity.
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.
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.
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).
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 15: Route "/search" used `searchParams.q`. `searchParams` should be awaited
Page props `searchParams` are a Promise in Next.js 15 and must be awaited.
TypeError: Cannot destructure property 'user' of 'useContext(...)' as it is undefined.
A component read a context with no matching Provider above it.
Error: No QueryClient set, use QueryClientProvider to set one
TanStack Query hooks ran outside a QueryClientProvider (or a duplicate copy of the library is installed).
Error: Functions cannot be passed directly to Client Components unless you explicitly expose it by marking it with "use server".
A Server Component passed a function prop to a Client Component.
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.
Next.js: ReferenceError: window is not defined (server-side rendering)
Code touching the browser's `window` ran on the server during SSR/build, where it doesn't exist.
Next.js: ReferenceError: document is not defined
Code used the DOM (`document`) while rendering on the server.
Next.js 15: Route "/x" used `cookies().get('token')`. `cookies()` should be awaited before using its value
Since Next.js 15, cookies(), headers(), params and searchParams are async — they must be awaited.
Next.js: useSearchParams() should be wrapped in a suspense boundary at page "/". Read more: https://nextjs.org/docs/messages/missing-suspense-with-csr-bailout
A Client Component using `useSearchParams` is statically rendered, so the build needs a Suspense boundary for the client-only par…
Next.js: Failed to compile. ./src/app/page.tsx:15:9 Type error: Type 'string | undefined' is not assignable to type 'string'
TypeScript type checking failed during `next build`, which blocks the deployment.
Next.js: Module not found: Can't resolve '@/components/Button' / 'lodash' in '/app/src'
Webpack/Turbopack couldn't resolve an import — wrong path/alias, missing dependency or case mismatch.
Next.js: Failed to compile. ./src/app/page.tsx 12:7 Error: 'x' is assigned a value but never used. @typescript-eslint/no-unused-vars
`next build` runs ESLint and fails the build on lint errors.
Next.js: TypeError: Failed to parse URL from /api/posts (fetch in a Server Component)
`fetch('/api/x')` with a relative URL works in browsers but not on the server, which has no base URL.
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.
Vue Router: Uncaught (in promise) NavigationDuplicated: Avoided redundant navigation to current location: "/home"
`router.push` to the route you're already on, rejecting the promise (Vue Router 3.1+).
Vue Router: [Vue warn]: injection "Symbol(router)" not found. / Cannot read properties of undefined (reading 'push')
`useRouter()`/`useRoute()` ran in a component tree where the router plugin isn't installed.
Browser: Cannot GET /users/42 — refreshing a Vue Router history-mode page returns 404
In history mode the server must serve `index.html` for all routes; otherwise direct URLs/refreshes hit non-existent files.
Vuex: [vuex] unknown mutation type: SET_USER / [vuex] unknown action type: fetchUser
`commit`/`dispatch` was called with a name that isn't registered in the store (or its module namespace).
Vuex (strict mode): Error: [vuex] do not mutate vuex store state outside mutation handlers.
Store state was modified directly (in a component or action) while strict mode is on.
Nuxt: [Vue warn]: Hydration completed but contains mismatches.
Server HTML and client render differed; Vue patched the DOM but logs the mismatch.
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