All Errors

This error occurs when mixing getInitialProps (often in _app.js) with getStaticProps in page components. Next.js prevents this combination because getInitialProps disables automatic static optimization and conflicts with build-time static generation.

This error occurs when trying to use class field syntax to initialize state without proper Babel configuration, or when the build tool doesn't support class properties. The state property must be assigned in the constructor using `this.state = {}` or class properties transform must be enabled.

The "Unexpected token ) in JSON" error occurs when your React application attempts to parse invalid JSON data. This typically happens when fetching data from an API and trying to parse the response, but the response is not valid JSON—often containing extra characters, syntax errors, or non-JSON content like HTML error pages.

This error occurs when attempting to access AsyncLocalStorage data outside of an asynchronous context initialized by run() or enterWith(). The store is only available within the callback scope or in operations properly bound to that context.

This webpack error occurs when files containing JSX, special syntax, or binary content are processed without the appropriate loader configured. The bundler attempts to parse the file as plain JavaScript but encounters characters it cannot understand.

This warning occurs when React attempts to update or interact with a component that has already been unmounted from the DOM. It typically happens when asynchronous operations like timers, API calls, or event listeners complete after the component has been removed, causing memory leaks and potential crashes.

This error occurs when React is not properly imported or in scope when JSX is used. It commonly happens due to missing import statements, incorrect bundler configuration, or issues with the React 17+ JSX transform.

This error occurs when attempting to render a plain JavaScript object directly in JSX. React requires you to render primitives, elements, or arrays, not raw objects.

This warning appears during React hydration when the className generated on the server differs from the one generated on the client. Commonly caused by CSS-in-JS libraries like styled-components, Material-UI, or conditional rendering that differs between server and client.

React event handlers may fail to prevent default behavior when preventDefault() is called incorrectly or when accessing synthetic events asynchronously. This commonly occurs when functions are invoked instead of passed as references, or when trying to access event properties in async callbacks.

This error occurs when a React component returns an invalid value like undefined, typically due to a missing return statement. In React versions before 18, components that returned undefined or false would throw this error, though React 18+ is more lenient with undefined returns.

This ESLint warning occurs when your useEffect hook references variables, props, or state that are not included in its dependency array. When dependencies are missing, your effect may run with stale values or fail to re-run when those values change, leading to bugs and unexpected behavior.

JSX syntax errors occur when React encounters improperly formatted HTML-like code that violates JSX rules. These errors commonly arise from unclosed tags, missing parent wrappers, or using HTML syntax instead of JSX conventions.

This error occurs when attempting to decode a base64 string that has incorrect padding. Base64 encoding requires padding to a multiple of 4 characters using the "=" character, and improper padding causes decoding failures in strict validation contexts.

This warning appears during server-side rendering when useLayoutEffect is called, because layout effects cannot run on the server where there is no DOM. React falls back to useEffect behavior, which can cause hydration mismatches between server and client renders.

React throws this error when a component's render() method or function component returns undefined instead of valid JSX, null, or other renderable values. This typically happens due to missing return statements or incorrect arrow function syntax.

The 'lost connection' error in SCP occurs when the SSH connection is unexpectedly dropped during file transfer. This can happen due to network issues, SSH protocol incompatibilities, or command path problems on the remote host.

React throws this error when you pass a string value where a component is expected. This commonly occurs when importing components incorrectly, passing component names as strings, or when dynamic component resolution fails.

This error occurs when useContext is called with an invalid argument, most commonly when passing Context.Consumer instead of the Context object itself, or when the Context Provider is missing from the component tree.

React error #130 occurs when an invalid element type is passed to React - expecting a string for built-in components or a class/function for custom components, but receiving something else like undefined, an object, or null.