yup.ValidationError ​

This is what Field.$error or FormsField.$error returns if there is an error.

Details of yup.ValidationError object ​

The README.md of yup explains the same things.

message property ​

• Error message (string).

const firstName = field("", yup.string().required())
console.log(firstName.$error.message); // "this is a required field"

const lastName = field("", yup.string().required("REQUIRED!"));
console.log(lastName.$error.message); // "REQUIRED!"

type property ​

• Error type such as "required" (string). This property is useful for testing because it is independent of error messages.

const firstName = field("", yup.string().required())
console.log(firstName.$error.type); // "required"

const lastName = field("", yup.string().required("REQUIRED!"));
console.log(lastName.$error.type); // "required"

errors property ​

• Array of error messages (string[]).
  • Field.$errorMessages and FormsField.$errorMessages can be used instead. These properties return an empty array if there are no errors.

inner property ​

• In the case of aggregate errors, inner is an array of ValidationError throw earlier in the validation chain.
• When the abortEarly option is false this is where you can inspect each error thrown, alternatively, errors will have all of the messages from each inner error.