jaredpalmer/formik · warning

Warning: Formik called \`${handlerName}\`, but you forgot to

Error message

Warning: Formik called \`${handlerName}\`, but you forgot to pass an \`id\` or \`name\` attribute to your input:\n    ${htmlContent}\n    Formik cannot determine which value to update. For more info see https://formik.org/docs/api/formik#${documentationAnchorLink}\n  

What it means

A `<Field>`/`<FastField>`-rendered input fired change or blur, and Formik's `handleChange`/`handleBlur` received an event whose target has neither `id` nor `name`. Without one of those attributes Formik cannot map the event to a key in `values`, so it warns (dev only) and the value is silently not updated.

Source

Thrown at packages/formik/src/Formik.tsx:1051

            )
          : !isEmptyChildren(children)
          ? React.Children.only(children)
          : null
        : null}
    </FormikProvider>
  );
}

function warnAboutMissingIdentifier({
  htmlContent,
  documentationAnchorLink,
  handlerName,
}: {
  htmlContent: string;
  documentationAnchorLink: string;
  handlerName: string;
}) {
  console.warn(
    `Warning: Formik called \`${handlerName}\`, but you forgot to pass an \`id\` or \`name\` attribute to your input:
    ${htmlContent}
    Formik cannot determine which value to update. For more info see https://formik.org/docs/api/formik#${documentationAnchorLink}
  `
  );
}

/**
 * Transform Yup ValidationError to a more usable object
 */
export function yupToFormErrors<Values>(yupError: any): FormikErrors<Values> {
  let errors: FormikErrors<Values> = {};
  if (yupError.inner) {
    if (yupError.inner.length === 0) {
      return setIn(errors, yupError.path, yupError.message);
    }
    for (let err of yupError.inner) {
      if (!getIn(errors, err.path)) {

View on GitHub (pinned to 91475adbf3)

Solutions

1. Ensure every input wired to Formik has a `name` (or `id`) attribute matching a key in initial values: `<Field name="email" ... />`.
2. In custom components, spread Formik's field props: `<input {...field} {...props} />`.
3. When calling handlers manually, pass a React SyntheticEvent whose target has a name: `handleChange({ target: { name: 'email', value } } as any)`.

Example fix

// before
<Field component={() => <input onChange={handleChange} />} />
// after
<Field name="email" component={() => <input name="email" onChange={handleChange} />} />
// or in custom components:
const MyInput = ({ field, form, ...props }) => <input {...field} {...props} />;

// lint/dev check: every Field must have a name
// react/jsx-props rule or a tiny wrapper
const SafeField = (props) => {
  if (process.env.NODE_ENV !== 'production' && !props.name) {
    console.error('<Field> requires a name');
  }
  return <Field {...props} />;
};

const hasIdentifier = (el: HTMLInputElement | null): el is HTMLInputElement & { name: string } =>
  !!el && (!!el.name || !!el.id);

// in custom components spread field so name/onChange/id propagate

// when invoking handlers manually, always include name
handleChange({
  target: { name: 'email', value: e.target.value },
} as React.ChangeEvent<HTMLInputElement>);

When it happens

Trigger: `<Field>` without `name` (e.g. `<Field component={CustomInput} />` where the custom component forgets to spread `field` onto the underlying `<input>`), passing `handleChange` to a non-standard component that swallows name, or manually calling `handleChange({ target: {} })`.

Common situations: Custom input components that don't spread `{...field}` or `{...props}`; copy-pasted `<input onChange={handleChange} />` without name; using handleBlur/handleChange with UI libraries requiring explicit `name` props.

Related errors

• Warning: An unhandled error was caught during validation in
• Warning: An unhandled error was caught during validation in
• Warning: An unhandled error was caught from submitForm()

AI-assisted analysis of jaredpalmer/formik@91475adbf3 (2026-08-27). Data as JSON: /api/errors/f1cd26af9e76cacc. Report an issue: GitHub.