Configuration options

The object passed to Bugsnag.start({ … }) can be used to configure and customize the behavior of the library when BugSnag starts. The Bugsnag client also provides operations that amend the state of the client whilst your application is running.

This documentation is for the latest BugSnag Expo libraries. Please see our guidance on support for Expo SDK 43 or earlier.


The API key used for events sent to BugSnag.

If you used the BugSnag Expo CLI to configure BugSnag, your API key will be added to your app.json and will be read from there when BugSnag starts. However it is also possible to set your API key through configuration:

Bugsnag.start({ apiKey: 'API_KEY' })

You can find your API key in Project Settings from your BugSnag dashboard.


If your app’s codebase contains different entry-points/processes, but reports to a single BugSnag project, you might want to add information denoting the type of process the error came from.

This information can be used in the dashboard to filter errors and to determine whether an error is limited to a subset of appTypes.

Bugsnag.start({ appType: 'rider' })
Bugsnag.start({ appType: 'passenger' })

The default appType in Expo is either "Android" or "iOS", depending on the platform the app is running on.


The version of the application. This is really useful for finding out when errors are introduced and fixed. Additionally BugSnag can re-open closed errors if a later version of the app has a regression.

The version from your app.json will be picked up automatically, but if you need to you can override it here:

Bugsnag.start({ appVersion: '4.10.0' })


By default, we will automatically notify BugSnag of any uncaught errors that we capture. Use this flag to disable all automatic detection.

Bugsnag.start({ autoDetectErrors: false })

Setting autoDetectErrors to false will disable all automatic errors, regardless of the error types enabled by enabledErrorTypes.


By default, BugSnag will automatically capture and report session information from your application. Use this flag to disable all automatic reporting.

Bugsnag.start({ autoTrackSessions: false })

BugSnag will automatically report a session each time:

  • The JS bundle is executed


The “context” is a string that indicates what the user was doing when an error occurs and is given high visual prominence in the dashboard. Set an initial context that you want to send with events – see Setting context for more information.

Bugsnag.start({ context: 'ctx-id-1234' })


A user-defined unique identifier for a JavaScript code deployment. There can be multiple deployments for a given appVersion.

For apps using EAS Update, use this configuration option to identify the update to BugSnag for matching source maps:

Bugsnag.start({ codeBundleId: Updates.manifest?.metadata?.updateGroup  })


By default BugSnag will automatically add breadcrumbs for common application events whilst your application is running. Set this option to configure which of these are enabled and sent to BugSnag.

  enabledBreadcrumbTypes: ['error', 'log', 'request', 'state']

Automatically captured breadcrumbs can be disabled by providing an empty array in enabledBreadcrumbTypes.

Bugsnag.start({ enabledBreadcrumbTypes: [] })

The following automatic breadcrumb types can be enabled:

Captured errors

error breadcrumbs are left when an error event is sent to the BugSnag API.

Log messages

log breadcrumbs are left when messages are written to the console.

Wrapping console methods to leave breadcrumbs has the side effect of messing with line numbers in log messages. Therefore when releaseStage='development' console breadcrumbs are disabled.

Network requests

request breadcrumbs are left for network requests initiated via the XMLHttpRequest constructor and fetch() calls. Metadata includes HTTP method, request URL and status code (if available).

State changes

state breadcrumbs are left when:

  • the application enters or exits the foreground
  • the device’s network connection changes state
  • the device’s orientation changes


BugSnag will automatically detect different types of error in your application. Set this option if you wish to control exactly which types are enabled.

  enabledErrorTypes: {
    unhandledExceptions: false,
    unhandledRejections: true

Setting autoDetectErrors to false will disable all automatic errors, regardless of the error types enabled by enabledErrorTypes.


By default, BugSnag will be notified of events that happen in any releaseStage. Set this option if you would like to change which release stages notify BugSnag.

Bugsnag.start({ enabledReleaseStages: [ 'production', 'staging' ] })


By default we will send error reports to and sessions to

If you are using BugSnag On-premise you’ll need to set these to your Event Server and Session Server endpoints. If the notify endpoint is set but the sessions endpoint is not, session tracking will be disabled automatically to avoid leaking session information outside of your server configuration, and a warning will be logged.

  endpoints: {
    notify: '',
    sessions: ''


Declare feature flag and experiment usage.

  featureFlags: [
    { name: 'Checkout button color', variant: 'Blue' },
    { name: 'Special offer', variant: 'Free Coffee' },
    { name: 'New checkout flow' },

See the Feature flags & experiments guide for more information.


By default, log messages from the BugSnag JavaScript library are prefixed with [bugsnag] and output to the console (if the platform has a useful console object). You can supply your own logger instead, or switch off logging completely by setting logger: null.

If you supply a logger, it must have the following methods: debug, info, warn and error.

// switch off logging
Bugsnag.start({ logger: null })

// supply a custom logger
var myCustomLogger = {
  debug: function () {},
  info: function () {},
  warn: function () {},
  error: function () {}
Bugsnag.start({ logger: myCustomLogger })


Sets the maximum number of breadcrumbs which will be stored. Once the threshold is reached, the oldest breadcrumbs will be deleted.

By default, 25 breadcrumbs are stored; this can be amended up to a maximum of 100.

Bugsnag.start({ maxBreadcrumbs: 40 })


Set diagnostic metadata that you want to send with all captured events – see Customizing error reports for more information.

  metadata: {
    company: {
      name: 'Acme Co.',
      country: 'uk'

The top-level keys of the supplied map are section names that are displayed as tabs in the BugSnag dashboard.


Add callbacks to modify or discard breadcrumbs before they are recorded — see Customizing breadcrumbs for more information.

  onBreadcrumb: function (breadcrumb) {
    if (breadcrumb.type === 'request') {
      if (breadcrumb.metadata.request === '/home') return false
      breadcrumb.metadata.request = stripQueryString(breadcrumb.metadata.request)

If log breadcrumbs are enabled, do not log within an onBreadcrumb callback to avoid an infinite loop.


Add callbacks to modify or discard error events before they are sent to BugSnag — see Customizing error reports for more information.

  onError: function (event) {
    // Adjust event here


Add callbacks to modify or discard sessions before they are sent to BugSnag — see Capturing sessions for more information.

  onSession: function (session) {
    var userId = getMyUserIdentifier() // a custom user resolver


Provide plugins for the client to use, along with any necessary arguments.

For example:

var Vue = require('vue')
var Bugsnag = require('@bugsnag/js')
var BugsnagPluginVue = require('@bugsnag/plugin-vue')
  plugins: [ new BugsnagPluginVue(Vue) ]


Sets which values should be removed from any metadata before sending them to BugSnag. Use this if you want to ensure you don’t transmit sensitive data such as passwords and credit card numbers.

Any property whose key matches a redacted key will be filtered and replaced with [REDACTED]. By default, any key that contains “password” will be redacted. Be aware that if you set this configuration option, it will replace the default, so you may want to replace “password” in your own set if you want to filter that.

The array can include both strings and regexes.

  redactedKeys: [
    'access_token', // exact match: "access_token"
    /^password$/i,  // case-insensitive: "password", "PASSWORD", "PaSsWoRd"
    /^cc_/          // prefix match: "cc_number" "cc_cvv" "cc_expiry"


Allows you to distinguish between errors that happen in different stages of the application release process (development, production, etc).

Bugsnag.start({ releaseStage: 'staging' })

If the application has been published with expo publish, or is running in a standalone application as a result of expo build:ios|android, releaseStage default to "production".

In development, if the application is running in “production mode” releaseStage will default to "local-prod", otherwise it will be "local-dev".


Set global user data that you want to send with all captured events – see Adding user data for more information.

  user: {
    id: '3',
    name: 'Bugs Nag',
    email: ''