Errors API - Feathers

Feathers provides a set of standard error classes that represent common HTTP errors. These errors work seamlessly across different transports (REST, WebSockets) and can be easily serialized and sent to clients.

FeathersError

The base class for all Feathers errors.

class FeathersError extends Error {
  constructor(
    message: ErrorMessage,
    name: string,
    code: number,
    className: string,
    data: any
  )
}

message

string | Error | object

required

The error message or an error object

name

string

required

The error name (e.g., 'BadRequest')

code

number

required

The HTTP status code (e.g., 400)

className

string

required

The class name in kebab-case (e.g., 'bad-request')

data

any

Additional error data

Properties

type

string

Always 'FeathersError'

code

number

The HTTP status code

className

string

The error class name in kebab-case

data

any

Additional error data

errors

any

Validation errors or sub-errors

Methods

toJSON()

Serialize the error to JSON:

toJSON(): FeathersErrorJSON

const error = new BadRequest('Invalid input', {
  field: 'email'
})

const json = error.toJSON()
// {
//   name: 'BadRequest',
//   message: 'Invalid input',
//   code: 400,
//   className: 'bad-request',
//   data: { field: 'email' }
// }

Error Classes

All error classes extend FeathersError and follow the same constructor pattern:

new ErrorClass(message?: ErrorMessage, data?: any)

4xx Client Errors

BadRequest (400)

General client error.

import { BadRequest } from '@feathersjs/errors'

throw new BadRequest('Invalid request parameters')

throw new BadRequest('Validation failed', {
  errors: {
    email: 'Email is required',
    password: 'Password must be at least 8 characters'
  }
})

NotAuthenticated (401)

User is not authenticated.

import { NotAuthenticated } from '@feathersjs/errors'

throw new NotAuthenticated('Authentication token missing')

throw new NotAuthenticated('Invalid credentials')

PaymentError (402)

Payment required or payment failed.

import { PaymentError } from '@feathersjs/errors'

throw new PaymentError('Payment required to access this resource')

throw new PaymentError('Credit card declined', {
  paymentId: '123',
  reason: 'insufficient_funds'
})

Forbidden (403)

User is authenticated but not authorized.

import { Forbidden } from '@feathersjs/errors'

throw new Forbidden('You do not have permission to access this resource')

throw new Forbidden('Admin access required')

NotFound (404)

Resource not found.

import { NotFound } from '@feathersjs/errors'

throw new NotFound('User not found')

throw new NotFound(`User with id ${id} does not exist`)

MethodNotAllowed (405)

HTTP method not allowed.

import { MethodNotAllowed } from '@feathersjs/errors'

throw new MethodNotAllowed('DELETE method is not allowed on this resource')

NotAcceptable (406)

Requested format is not available.

import { NotAcceptable } from '@feathersjs/errors'

throw new NotAcceptable('Only JSON format is supported')

Timeout (408)

Request timeout.

import { Timeout } from '@feathersjs/errors'

throw new Timeout('Request took too long to process')

Conflict (409)

Request conflicts with current state.

import { Conflict } from '@feathersjs/errors'

throw new Conflict('A user with this email already exists')

throw new Conflict('Resource version mismatch', {
  currentVersion: 2,
  requestedVersion: 1
})

Gone (410)

Resource is permanently gone.

import { Gone } from '@feathersjs/errors'

throw new Gone('This resource has been permanently deleted')

LengthRequired (411)

Content-Length header required.

import { LengthRequired } from '@feathersjs/errors'

throw new LengthRequired('Content-Length header is required')

Unprocessable (422)

Request is well-formed but contains semantic errors.

import { Unprocessable } from '@feathersjs/errors'

throw new Unprocessable('Cannot process this request', {
  reason: 'duplicate_entry'
})

TooManyRequests (429)

Rate limit exceeded.

import { TooManyRequests } from '@feathersjs/errors'

throw new TooManyRequests('Rate limit exceeded. Try again in 60 seconds', {
  retryAfter: 60
})

5xx Server Errors

GeneralError (500)

General server error.

import { GeneralError } from '@feathersjs/errors'

throw new GeneralError('An unexpected error occurred')

NotImplemented (501)

Feature not implemented.

import { NotImplemented } from '@feathersjs/errors'

throw new NotImplemented('This feature is not yet implemented')

BadGateway (502)

Bad gateway or upstream server error.

import { BadGateway } from '@feathersjs/errors'

throw new BadGateway('Upstream service is unavailable')

Unavailable (503)

Service temporarily unavailable.

import { Unavailable } from '@feathersjs/errors'

throw new Unavailable('Service is under maintenance', {
  retryAfter: 3600
})

Error Object Formats

Error Message Types

type ErrorMessage = 
  | null 
  | string 
  | Error 
  | { message?: string; errors?: any; [key: string]: any } 
  | any[]

Errors can be created with various input formats:

// String message
throw new BadRequest('Invalid input')

// Object with message and data
throw new BadRequest({
  message: 'Validation failed',
  errors: {
    email: 'Invalid format',
    age: 'Must be positive'
  }
})

// Existing Error object
try {
  await dangerousOperation()
} catch (err) {
  throw new GeneralError(err)
}

// Additional data as second parameter
throw new NotFound('User not found', {
  userId: 123,
  timestamp: new Date()
})

JSON Format

interface FeathersErrorJSON {
  name: string
  message: string
  code: number
  className: string
  data?: any
  errors?: any
}

Error Handling

In Hooks

const handleError = async (context) => {
  const { error } = context
  
  // Log the error
  console.error(`Error in ${context.path}.${context.method}:`, error)
  
  // Transform unknown errors
  if (!(error instanceof FeathersError)) {
    context.error = new GeneralError('An unexpected error occurred')
  }
}

app.hooks({
  error: {
    all: [handleError]
  }
})

In Services

class UserService {
  async get(id, params) {
    const user = await db.users.findById(id)
    
    if (!user) {
      throw new NotFound(`User ${id} not found`)
    }
    
    // Check authorization
    if (user.id !== params.user?.id && !params.user?.isAdmin) {
      throw new Forbidden('You can only access your own user data')
    }
    
    return user
  }
  
  async create(data, params) {
    // Validate input
    if (!data.email) {
      throw new BadRequest('Email is required')
    }
    
    // Check for duplicates
    const existing = await db.users.findByEmail(data.email)
    if (existing) {
      throw new Conflict('A user with this email already exists')
    }
    
    return await db.users.create(data)
  }
}

With Try/Catch

try {
  const user = await app.service('users').get(123)
} catch (error) {
  if (error instanceof NotFound) {
    console.log('User does not exist')
  } else if (error instanceof Forbidden) {
    console.log('Access denied')
  } else {
    console.error('Unexpected error:', error)
  }
}

Converting Errors

Convert plain error objects to Feathers errors:

import { convert } from '@feathersjs/errors'

const error = {
  name: 'NotFound',
  message: 'User not found',
  data: { userId: 123 }
}

const feathersError = convert(error)
// Returns: NotFound instance

error

any

required

Error object or value to convert

result

Error

A FeathersError instance if the error name matches, otherwise a generic Error

Accessing Errors by Code

Errors can be accessed by their HTTP status code:

import { errors } from '@feathersjs/errors'

const NotFoundError = errors[404]
throw new NotFoundError('Resource not found')

const BadRequestError = errors[400]
throw new BadRequestError('Invalid input')

Type Definitions

import {
  FeathersError,
  BadRequest,
  NotAuthenticated,
  PaymentError,
  Forbidden,
  NotFound,
  MethodNotAllowed,
  NotAcceptable,
  Timeout,
  Conflict,
  Gone,
  LengthRequired,
  Unprocessable,
  TooManyRequests,
  GeneralError,
  NotImplemented,
  BadGateway,
  Unavailable,
  errors,
  convert
} from '@feathersjs/errors'

interface FeathersErrorJSON {
  name: string
  message: string
  code: number
  className: string
  data?: any
  errors?: any
}

type ErrorMessage = 
  | null 
  | string 
  | Error 
  | { message?: string; errors?: any; [key: string]: any } 
  | any[]

Complete Error List

Class	Code	Description
BadRequest	400	General client error
NotAuthenticated	401	User not authenticated
PaymentError	402	Payment required/failed
Forbidden	403	User not authorized
NotFound	404	Resource not found
MethodNotAllowed	405	HTTP method not allowed
NotAcceptable	406	Requested format unavailable
Timeout	408	Request timeout
Conflict	409	Request conflicts with state
Gone	410	Resource permanently deleted
LengthRequired	411	Content-Length required
Unprocessable	422	Semantic error in request
TooManyRequests	429	Rate limit exceeded
GeneralError	500	General server error
NotImplemented	501	Feature not implemented
BadGateway	502	Upstream server error
Unavailable	503	Service unavailable

Core

Authentication

Databases

Transports

Schema

Utilities

​FeathersError

​Properties

​Methods

​toJSON()

​Error Classes

​4xx Client Errors

​BadRequest (400)

​NotAuthenticated (401)

​PaymentError (402)

​Forbidden (403)

​NotFound (404)

​MethodNotAllowed (405)

​NotAcceptable (406)

​Timeout (408)

​Conflict (409)

​Gone (410)

​LengthRequired (411)

​Unprocessable (422)

​TooManyRequests (429)

​5xx Server Errors

​GeneralError (500)

​NotImplemented (501)

​BadGateway (502)

​Unavailable (503)

​Error Object Formats

​Error Message Types

​JSON Format

​Error Handling

​In Hooks

​In Services

​With Try/Catch

​Converting Errors

​Accessing Errors by Code

​Type Definitions

​Complete Error List

FeathersError

Properties

Methods

toJSON()

Error Classes

4xx Client Errors

BadRequest (400)

NotAuthenticated (401)

PaymentError (402)

Forbidden (403)

NotFound (404)

MethodNotAllowed (405)

NotAcceptable (406)

Timeout (408)

Conflict (409)

Gone (410)

LengthRequired (411)

Unprocessable (422)

TooManyRequests (429)

5xx Server Errors

GeneralError (500)

NotImplemented (501)

BadGateway (502)

Unavailable (503)

Error Object Formats

Error Message Types

JSON Format

Error Handling

In Hooks

In Services

With Try/Catch

Converting Errors

Accessing Errors by Code

Type Definitions

Complete Error List