Error map
Could not find a production build in the '.next' directory 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.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)
Failed to load module script: Expected a JavaScript module script but the server responded with a MIME type of "text/html"
A or dynamic import got HTML back instead of JavaScript.
Refused to execute script from 'x' because its MIME type ('text/html') is not executable
The browser fetched a script but the server labelled it text/html (usually an error page), so it refused to run it.
SyntaxError: Unexpected token '<' (HTML served instead of JavaScript)
The browser loaded a .js file but received HTML (an error page or the SPA index.html).
ChunkLoadError: Loading chunk 123 failed.
A lazily loaded JavaScript chunk couldn’t be downloaded — usually because a new deployment removed the old hashed files.
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.
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: 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: 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).
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.
Two steps away (36)
Azure App Service: ":( Application Error" / container didn’t respond to HTTP pings
App Service started your app but it crashed or never listened on the expected port.
Could not load file or assembly 'X, Version=…' or one of its dependencies
The runtime couldn’t find or load a referenced DLL — missing from the output, wrong version, or wrong platform (x86/x64).
PHP still runs old code after deploy (OPcache not reset)
OPcache keeps serving cached bytecode, so changes uploaded to the server don’t take effect.
The framework 'Microsoft.NETCore.App', version '8.0.0' (x64) was not found. You must install or update .NET to run this application
The machine doesn’t have the .NET runtime version the app was built for (framework-dependent deployment).
Console: Refused to apply style from 'https://…/style.css' because its MIME type ('text/html') is not a supported stylesheet MIME type
The stylesheet URL returned something that is not CSS — usually a 404/HTML error page — and `X-Content-Type-Options: nosniff` mak…
Console: Failed to register a ServiceWorker: A bad HTTP response code (404) was received when fetching the script
The browser could not fetch, parse or install the service worker script, or the page is not allowed to register one (HTTPS and sc…
SyntaxError: Unexpected token < in JSON at position 0
`JSON.parse()` / `response.json()` received something that isn’t JSON — very often an HTML error page.
SyntaxError: missing ) after argument list
A function call’s parentheses are unbalanced — often an unescaped quote or a missing comma/plus.
SyntaxError: Identifier 'x' has already been declared
The same let/const/class name was declared twice in the same scope.
DOMException: Failed to execute 'querySelector' on 'Document': 'x' is not a valid selector
The CSS selector string is invalid — often an ID starting with a digit or containing special characters.
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.
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…
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…).
TypeError: x is not a constructor
new was used with something that isn’t a class/constructor — usually a wrong import.
ReferenceError: Cannot access 'x' before initialization
A let/const/class was used before its declaration line ran (temporal dead zone) — often a circular import.
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.
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts"
Node tried to run a TypeScript file as ESM without a TypeScript loader.
TS2307: Cannot find module 'x' or its corresponding type declarations.
TypeScript can’t resolve the import — the package isn’t installed, the path alias isn’t configured, or there are no types.
TS7016: Could not find a declaration file for module 'x'. 'x.js' implicitly has an 'any' type.
The JavaScript package has no TypeScript types bundled and no @types package installed.
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.
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.
Firebase Hosting: Page Not Found — This file does not exist and there was no 404.html or index.html found in the document root
A single-page app route returns 404 when opened directly or refreshed, because Firebase Hosting looks for a real file at that pat…
Next.js: Error: Failed to find Server Action "abc123". This request might be from an older or newer deployment
The browser called a Server Action ID the current server build doesn't know — usually a version skew after a deploy.
Vue: TypeError: Failed to fetch dynamically imported module: https://app.example.com/assets/Settings-abc123.js
A lazy-loaded route/component chunk couldn't be loaded (new deployment removed old chunks, network issue, or wrong base path).
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Popular: 500403400ORA-009331064Critical errorFileNotFoundException assemblyTypeError