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)

CORS blocked (Laravel API) 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 CORS blocked in Rails API (rack-cors) Browser: Access to fetch at 'http://localhost:3000/api/items' from origin 'http://localhost:5173' has been blocked by CORS policy — Rails createContext only works in Client Components 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" ERESOLVE: next requires react ^18 (peer dependency conflict) npm: ERESOLVE unable to resolve dependency tree — Found: react@19.0.0 / Could not resolve dependency: peer react@"^18.2.0" from some-lib ERR_TOO_MANY_REDIRECTS (Next.js middleware) Browser: This page isn't working — redirected you too many times (ERR_TOO_MANY_REDIRECTS) with Next.js middleware / trailing slash Failed prop type: The prop href expects a string or object in <Link> Next.js: Error: Failed prop type: The prop `href` expects a `string` or `object` in `<Link>`, but got `undefined` instead Hydration error: <div> cannot be a descendant of <p> 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 Image with src must use "width" and "height" properties or "fill" Next.js: Image with src "https://example.com/a.jpg" must use "width" and "height" properties or "fill" property Invalid <Link> with <a> child. Please remove <a> Next.js 13+: Error: Invalid <Link> with <a> child. Please remove <a> or use <Link legacyBehavior> Invalid hook call (duplicate React in Next.js) Next.js: Error: Invalid hook call. Hooks can only be called inside of the body of a function component — Cannot read properties of null (reading 'useContext') Invalid next.config.js options detected Next.js: Invalid next.config.js options detected: Unrecognized key(s) in object: 'xyz' next build: fetch failed ECONNREFUSED (build-time API) Next.js: Error occurred prerendering page "/blog" TypeError: fetch failed { cause: Error: connect ECONNREFUSED 127.0.0.1:3000 } next build: JavaScript heap out of memory Next.js: FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory (during next build) next.config.js: ES Module / require error Next.js: Error [ERR_REQUIRE_ESM]: require() of ES Module next.config.js / SyntaxError: Unexpected token 'export' No HTTP methods exported in route.ts Next.js: Error: No HTTP methods exported in '/app/api/users/route.ts'. Export a named export for each HTTP method (GET, POST...) 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 process.env.X is undefined in the browser (NEXT_PUBLIC_) Next.js: process.env.API_URL is undefined in Client Component / env variable not available in the browser Route used params.x — params should be awaited Next.js 15: Error: Route "/blog/[slug]" used `params.slug`. `params` should be awaited before using its properties searchParams should be awaited (Next.js 15) Next.js 15: Route "/search" used `searchParams.q`. `searchParams` should be awaited Server actions must be async functions Next.js: Error: Server actions must be async functions 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')