Error map
refs on function components Warning: Function components cannot be given refs. Attempts to access this ref will fail. Did you mean to use React.forwardRef()?
React · 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)
Warning: An update to Component inside a test was not wrapped in act(...)
A component updated state after the test’s synchronous assertions — async work wasn’t awaited.
Vue: [Vue warn]: Failed to resolve component: x
The template uses a component tag that isn’t registered or imported where it’s used.
Adjacent JSX elements must be wrapped in an enclosing tag. Did you want a JSX fragment <>...</>?
A component returns two sibling JSX elements without a single parent.
Warning: Cannot update a component (`Parent`) while rendering a different component (`Child`)
A child component updated a parent’s state during its render instead of in an effect or event handler.
Warning: A component is changing an uncontrolled input to be controlled
An input’s `value` started as `undefined` (uncontrolled) and later became a defined value (controlled), or vice versa.
error: cannot lock ref 'refs/remotes/origin/x': is at … but expected … / unable to update local ref
Git couldn’t update a reference — stale remote-tracking refs, case-only branch name clashes, or a leftover lock file.
warning: ignoring broken ref refs/remotes/origin/HEAD
A ref file is empty or points to a missing object — usually refs/remotes/origin/HEAD after the default branch changed.
Warning: componentWillMount has been renamed, and is not recommended for use.
A class component uses legacy lifecycle methods (componentWillMount/WillReceiveProps/WillUpdate).
Two steps away (23)
Node.js: [UnhandledPromiseRejection] — This error originated either by throwing inside of an async function without a catch block
A promise rejected and nothing handled it; since Node 15 this crashes the process.
SyntaxError: await is only valid in async functions and the top level bodies of modules
await was used inside a function that isn’t async (or in a classic, non-module script).
AbortError: The user aborted a request. / signal is aborted without reason
A fetch was cancelled through an AbortController (or the browser cancelled it).
Vue: [Vue warn]: Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders
A child component assigned to a prop. Props flow one way — the parent owns the value.
Vue: [Vue warn]: Property "x" was accessed during render but is not defined on instance
The template references a variable/function that the component doesn’t expose.
Error: Objects are not valid as a React child
You tried to render a plain object (or a Promise/Date) directly in JSX; React can only render strings, numbers, elements and arra…
SyntaxError: Invalid regular expression: /x/: Unterminated group
A regex pattern has invalid syntax — unbalanced parentheses/brackets or unescaped special characters.
Error: Nothing was returned from render. This usually means a return statement is missing.
A component returned undefined (React 17 and earlier) — usually a missing return or a return followed by a line break.
Error: Too many re-renders. React limits the number of renders to prevent an infinite loop.
A state update runs during render, which triggers another render, which updates state again — forever.
Warning: Each child in a list should have a unique "key" prop
When rendering a list with `.map()`, each element needs a stable, unique `key` so React can track items between renders.
java.lang.IllegalStateException
A method was called when the object wasn’t in the right state for it.
TypeError: Cannot read properties of undefined (reading 'x')
You tried to access a property on a value that is `undefined` (or `null`) — usually data that hasn’t loaded yet or a wrong proper…
TypeError: Cannot assign to read only property 'x' of object
Code tried to modify a frozen object, a getter-only property, or immutable state.
Warning: validateDOMNesting(...): <div> cannot appear as a descendant of <p>.
The JSX produces invalid HTML nesting, which also causes hydration mismatches in SSR.
error: The following untracked working tree files would be overwritten by checkout/merge
Untracked local files have the same paths as files coming from the other branch.
error: remote origin already exists.
A remote named origin is already configured.
remote: Repository not found. fatal: repository 'https://github.com/x/y.git/' not found
GitHub/GitLab says the repository doesn’t exist — or you lack access to a private repo.
! [remote rejected] main -> main (branch is currently checked out)
You pushed to a non-bare repository whose working tree has that branch checked out.
fatal: 'origin' does not appear to be a git repository
No remote named origin is configured (or it points nowhere valid).
fatal: couldn't find remote ref main
The branch you tried to pull/fetch doesn’t exist on the remote.
DeprecationWarning: Buffer() is deprecated due to security and usability issues (DEP0005)
Code (yours or a dependency) uses the deprecated new Buffer() constructor.
DeprecationWarning: The `punycode` module is deprecated (DEP0040)
A dependency imports Node’s built-in punycode module, deprecated since Node 21.
npm WARN deprecated package@1.2.3: This package is no longer supported.
A dependency (often a transitive one) is deprecated by its author.
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