Error map
Module not found: Can't resolve 'x' (Next.js build) Next.js: Module not found: Can't resolve '@/components/Button' / 'lodash' in '/app/src'
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)
ReferenceError: Cannot access 'x' before initialization
A let/const/class was used before its declaration line ran (temporal dead zone) — often a circular import.
TypeError: x is not a function
You called something as a function, but its value is not a function (it’s undefined, a string, an object…).
Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined
JSX referenced a component that is undefined — almost always a default/named import mismatch.
TypeError: x is not a constructor
new was used with something that isn’t a class/constructor — usually a wrong import.
TypeError: Router.use() requires a middleware function but got a Object
app.use()/router.use() received an object instead of a function — usually a router module that wasn’t exported.
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.
Vue: [Vue warn]: Component is missing template or render function.
A component object has neither `template` nor `render`, or an SFC import resolved wrongly.
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: 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: ⨯ Failed to download `Inter` from Google Fonts. Using fallback font instead / FetchError: request to https://fonts.googleapis.com failed
`next/font/google` couldn't download the font at build/dev time (offline, firewall or proxy).
Vue: [Vue warn]: Component provided template option but runtime compilation is not supported in this build of Vue. Configure your bundler to alias "vue" to "vue/dist/vue.esm-bundler.js"
A component uses a string `template` but the runtime-only Vue build has no compiler.
Two steps away (36)
ReferenceError: x is not defined
Code refers to a variable or function name that doesn’t exist in the current scope.
NameError: name 'x' is not defined
Python doesn’t know the name — it was never assigned/imported in this scope, or it’s misspelled.
SyntaxError: Identifier 'x' has already been declared
The same let/const/class name was declared twice in the same scope.
Error: Cannot find module 'x' (MODULE_NOT_FOUND)
Node can’t resolve the module path — the package isn’t installed, or a relative path/extension is wrong.
TypeError: Cannot read properties of undefined (reading 'x')
You tried to access a property on a value that is `undefined` (or `null`) — usually data that hasn’t loaded yet or a wrong proper…
AttributeError: 'X' object has no attribute 'y'
You accessed an attribute or method that doesn’t exist on that object type.
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: Too many re-renders. React limits the number of renders to prevent an infinite loop.
A state update runs during render, which triggers another render, which updates state again — forever.
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.
MySQL ERROR 1046 (3D000): No database selected
A query referenced tables without a database selected (no USE and no db in the connection).
MySQL ERROR 1153 (08S01): Got a packet bigger than 'max_allowed_packet' bytes
A single statement or row exceeded max_allowed_packet — big BLOBs, huge INSERTs or large dump lines.
MySQL ERROR 1227 (42000): Access denied; you need (at least one of) the SUPER privilege(s) for this operation
The import or statement needs SUPER/SYSTEM_VARIABLES_ADMIN — typical with dumps containing DEFINER clauses or SET GLOBAL on manag…
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
An Express/Node handler tried to send a second response (or set headers) after one was already sent.
Express: req.body is undefined / {} (body parser missing)
Express didn’t parse the request body because no body-parsing middleware matched the request’s Content-Type.
TypeError: Missing parameter name at 1 (path-to-regexp)
An Express 5 (path-to-regexp v8) route uses old wildcard syntax like '*' or '/:id?'.
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.
ChunkLoadError: Loading chunk 123 failed.
A lazily loaded JavaScript chunk couldn’t be downloaded — usually because a new deployment removed the old hashed files.
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.
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.
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.
React Hook useEffect has a missing dependency (react-hooks/exhaustive-deps)
ESLint warns that the effect reads a value that isn’t in its dependency array, so it may use a stale value.
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.
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.
RangeError: Invalid string length
A string grew beyond the engine’s maximum length — usually runaway concatenation or huge JSON.stringify output.
MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 listeners added
More than 10 listeners were added to one event — often a leak where listeners are added repeatedly.
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).
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.
'react-scripts' is not recognized as an internal or external command / react-scripts: command not found
node_modules is missing or broken, so the react-scripts binary isn’t available.
npm ERR! code ETIMEDOUT — network request to https://registry.npmjs.org/x failed, reason: connect ETIMEDOUT
npm couldn’t reach the registry in time — network, proxy or firewall issue.
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: Error: Could not find a production build in the '.next' directory. Try building your app with 'next build' before starting the production server
`next start` was run without a prior successful `next build` (or the `.next` folder is missing).
Module parse failed: Unexpected token. You may need an appropriate loader to handle this file type
Webpack found syntax it can’t parse because no loader is configured for that file (JSX, TypeScript, CSS, or modern syntax in node…
Vue: [Vue warn]: Failed to resolve component: x
The template uses a component tag that isn’t registered or imported where it’s used.
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…
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