Error map
Only plain objects can be passed to Client Components 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
Next.js · layer 1, On your device
Centre: this error. First ring: errors it is linked with (8). 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 (8)
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.
CastError: Cast to ObjectId failed for value "x" (type string) at path "_id"
A value that isn’t a valid 24-hex-character ObjectId was used in an _id query.
TypeError: Converting circular structure to JSON
JSON.stringify met an object that references itself (directly or through children).
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.
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`.
Two steps away (24)
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.
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.
HTTP 422 Unprocessable Content
The request is well-formed, but the data fails validation (e.g. invalid email, missing required field).
java.lang.NumberFormatException: For input string: "x"
A string couldn’t be parsed as a number — it’s empty, has spaces/commas, is too large, or isn’t numeric.
java.lang.IllegalArgumentException
A method rejected an argument value as invalid.
SyntaxError: Unexpected token < in JSON at position 0
`JSON.parse()` / `response.json()` received something that isn’t JSON — very often an HTML error page.
JsonException: A possible object cycle was detected
System.Text.Json found a reference loop (e.g. Order → Customer → Orders → …) while serialising, usually from EF Core navigation p…
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `java.util.ArrayList` from Object value
Jackson found JSON whose shape doesn’t match the target Java type (object vs array, string vs number, missing constructor).
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.
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: 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.
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.
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.
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