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Frequently Asked Questions

Below are a number of questions or issues that have arisen from using the SDK.

Why is the user logged out when they refresh the page in their SPA?

After logging in, if the page is refreshed and the user appears logged out, it usually means that the silent authentication step has failed to work.

This could be affected by a couple of things:

Please try these to see if you can get unblocked:

  • Try it in a browser like Chrome which does not block third-party cookies by default (yet)
  • Use the New Login Experience, if possible
  • Supply the social connection with your own client ID and secret in the Auth0 dashboard

Using Multi-factor Authentication (MFA)

By default, auth0-spa-js uses the prompt=none and response_mode=web_message flow for silent auth, which depends on the user's Auth0 session.

If you have "Require Multi-factor Auth" set to "Always" in your Auth0 Dashboard, silent authentication from your SPA will fail unless:

  • The user is using a one-time code and selects "Remember me for 30 days"
  • allowRememberBrowser is configured in a Rule and provider is set to google-authenticator

If silent auth is being used and Auth0 needs interaction from the user to complete the MFA step, then authentication will fail with an mfa_required error and the user must log in interactively.

To resolve this:

Why does the Auth0Client object take a long time to initialize?

Sometimes the createAuth0Client asynchronous method can take over 30 seconds to complete. createAuth0Client may also return undefined and produce an error when you try to access it.

This is usually down to a configuration problem between your application, and the Auth0 application you're trying to log in with. Things to check:

  • Make sure that options passed to createAuth0Client include the correct client ID and domain values for the app you're using
  • Ensure that the Allowed Callback URLs, Allowed Web Origins, and Allowed Logout URLs are correctly set up in your Auth0 app settings for your application

To verify that you're hitting this problem, check the logs in your Auth0 dashboard for any failed login events, which may provide a clue as to the problem.

Why do I get an "invalid algorithm" error?

The SDK only supports JWTs that use the RS256 signing algorithm. If you're getting this error, it's likely that the Auth0 application you're authenticating with is set up to sign tokens using HS256.

The way around this error is to change the settings for your Auth0 application to sign tokens using RS256. To do this:

  • Log in to your dashboard
  • Open the settings page for the application you're using
  • Scroll to the bottom and click Show advanced settings
  • Click the OAuth tab
  • Ensure the JsonWebToken Signature Algorithm value is set to RS256
  • Click Save

The next time you try to authenticate, you should not receive this error.

Why do I get auth0-spa-js must run on a secure origin?

Internally, the SDK uses Web Cryptography API to create SHA-256 digest.

According to the spec (via Github issues), Web Cryptography API requires a secure origin, so that accessing Crypto.subtle in a not secure context return undefined.

In most browsers, secure origins are origins that match at least one of the following (scheme, host, port) patterns:

(https, *, *)
(wss, *, *)
(*, localhost, *)
(*, 127/8, *)
(*, ::1/128, *)
(file, *, —)

If you're running your application from a secure origin, it's possible that your browser doesn't support the Web Crypto API. For a compatibility table, please check https://caniuse.com/#feat=mdn-api_subtlecrypto

Why am I getting a missing_refresh_token error after upgrading to v2?

v1 of the SDK used an iframe as a backup if no refresh token was available. You could control this behaviour with the useRefreshTokensFallback option, which was true by default. With v2, we have flipped the default for useRefreshTokensFallback to false (see the migration guide). As a result, you may encounter missing_refresh_token errors.

To mitigate this, use one of the following solutions:

  • Handle the error, and log the user in again using loginWithRedirect or loginWithPopup.
  • Revert to the v1 behaviour by setting useRefreshTokensFallback to true.

In all cases, the fallback will not work in browsers where third-party cookies are blocked, unless you are using custom domains.

Why is the passwordless magic link not working?

By default, the SDK stores transactional data in the browser's session storage. This means that the authentication flow needs to be finished in the same browser tab it was started. This can cause issues when using passwordless with magic links, as that typically opens in a new tab. To solve this, our SDK can be configured to store the transactional data in a cookie instead of session storage:

new Auth0Client({
  useCookiesForTransaction: true
});

How to use from a CDN

There are two ways to use our SDK when you want to rely on a Content Delivery Network to host the bundle and not install our SDK through the npm registry.

Using our own CDN bundle

Our own CDN bundle exposes both createAuth0Client and Auth0Client on a global auth0 variable, and can be used as shown below.

<script>
  const client = auth0.createAuth0Client({ ... });
  // or
  const client = new auth0.Auth0Client({ ... });
</script>

Using import maps with unpkg

If you want to use a CDN bundle together with import maps, you will need to use our ESM bundle from unpkg:

<script type="importmap">
  {
    "imports": {
      "@auth0/auth0-spa-js": "https://www.unpkg.com/@auth0/auth0-spa-js@2.1.3/dist/auth0-spa-js.production.esm.js"
    }
  }
</script>
<script type="module">
  import { createAuth0Client, Auth0Client } from '@auth0/auth0-spa-js';

  const client = createAuth0Client({ ... });
  // or
  const client = new Auth0Client({ ... });
</script>

Why is isAuthenticated returning true when there are no tokens available to call an API?

As long as the SDK has an id token, you are considered authenticated, because it knows who you are. It might be that there isn't a valid access token and you are unable to call an API, but the SDK still knows who you are because of the id token.

Authentication is about who you are (id token), not what you can do (access token). The latter is authorization, which is also why you pass the access token to the API in the Authorization header.

So even when the refresh token fails, or getTokenSilently returns nothing, that doesn't impact the existence of the id token, and as a consequence of that, the authentication state. So it's expected for isAuthenticated to stay true in that case.

On top of that, the SDK can have multiple access tokens and multiple refresh tokens (e.g. when using multiple audience and scope combinations to call multiple API's), but only one id token. If there are multiple access and refresh tokens, and one of the refresh tokens fails, it doesn't mean the other access tokens or refresh tokens are invalid, they might still be perfectly usable.

The Token Worker is being blocked by my Content-Security-Policy (CSP), what should I do?

When using refresh tokens - along with the default in-memory cache - the SDK will leverage a Worker to globally isolate the refresh token from the rest of your application.

By default, to reduce the friction of getting started with the SDK, we ship that Worker code with the main SDK bundle and dynamically pass it as a string to create a new Worker.

Unless configured to allow for that, Content-Security-Policy (CSP) will block the loading of the dynamic blob:.

To allow you to keep strict Content-Security-Policy (CSP), and not have to allow blob: in your CSP, we also ship the Worker as a separate compiled JavaScript file. You can find that file in ./dist/auth0-spa-js.worker.production.js or on our CDN. This allows you to either copy the worker JavaScript file to your web server's public assets folder or load it from our CDN.

For example, if I have a folder called static in the root of my project then I could update my build script to copy the worker file to it:

my-build-script && cp ./node_modules/@auth0/auth0-spa-js/dist/auth0-spa-js.worker.development.js ./static/

Now when instantiating the SDK, I can configure it to load the worker code from that location:

import { createAuth0Client, Auth0Client } from '@auth0/auth0-spa-js';

const client = createAuth0Client({
  ...
  workerUrl: '/static/auth0-spa-js.worker.production.js'
});
// or
const client = new Auth0Client({
  ...
  workerUrl: '/static/auth0-spa-js.worker.production.js'
});

In this case, the loading of the Worker would comply with a CSP that included 'self'. You can follow similar steps if you'd prefer to copy the file to your own CDN instead.