Error map
Failed to find Server Action Next.js: Error: Failed to find Server Action "abc123". This request might be from an older or newer deployment
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: ⨯ 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: 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: Error: Server actions must be async functions
A function marked `"use server"` isn't declared `async`.
Next.js: Error: Body exceeded 1 MB limit. To configure the body size limit for Server Actions, see: https://nextjs.org/docs/app/api-reference/next-config-js/serverActions#bodysizelimit
A Server Action (often a file upload) sent more than the default 1 MB request body.
Vercel: 504 GATEWAY_TIMEOUT — FUNCTION_INVOCATION_TIMEOUT: An error occurred with your deployment
A Vercel Serverless Function ran longer than its max duration, so Vercel killed it.
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.
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).
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: 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.
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.
Next.js: Error: Only plain objects, and a few built-ins, can be passed to Client Components from Server Components. Classes or null prototypes are not supported
A Server Component passed a non-serialisable value (class instance, Date-like object, Mongoose doc, Map) as a prop to a Client Co…
Next.js: Error: Route /blog used "revalidatePath /blog" during render which is unsupported. It must happen outside of renders and cached functions
`revalidatePath`/`revalidateTag` was called while rendering a page or component, not from an action or route handler.
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.
HTTP 413 Content Too Large (Request Entity Too Large)
The request body is bigger than the server is willing to accept — usually a file upload over the configured limit.
Vercel: 413 FUNCTION_PAYLOAD_TOO_LARGE — Request Entity Too Large (4.5 MB limit)
A request or response exceeded Vercel's 4.5 MB serverless function payload limit.
Nginx: [error] client intended to send too large body: 5242880 bytes (413 Request Entity Too Large)
A request body exceeded `client_max_body_size` (default 1 MB), so Nginx returned 413 before reaching your app.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
Vercel: Error: Command "npm run build" exited with 1
The Vercel build step failed; the real reason is printed in the build log above this line.
Vercel: The Edge Function "middleware" size is 1.2 MB and your plan size limit is 1 MB. Learn More: https://vercel.link/edge-function-size
Your middleware/Edge Function bundle is larger than the plan's size limit.
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…
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).
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).
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: 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.
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