Auth0 `loginWithPopup` error and workaround

I recently integrated Auth0 Universal Login into a React SPA but had a problem with the loginWithPopup flow (from the @auth0/auth0-react library).

The popup would open, allowing the user to log in. But then on success, the Auth0 redirect would result in the following error:

Failed to execute 'postMessage' on 'DOMWindow':
  The target origin provided ('http://my-origin') does not match the recipient window's origin ('').

This error prevented the login flow from completing.

I wasn’t able to find much information online about this problem. But after much pain and experimentation, the issue turned out be caused by crossOriginIsolated being true on my site, which is enabled by the following headers:

Cross-Origin-Embedder-Policy: require-corp
Cross-Origin-Opener-Policy: same-origin

crossOriginIsolated is needed to unlock browser features such as SharedArrayBuffer and Since my application requires these features, I needed to find a workaround that had a similar UX to Auth0’s loginWithPopup.


Here is a high-level overview of my workaround:

  1. On the login page, register an event listener for local storage. We will be listening for a change to an isLoggedIn flag set in the popup window.
  2. When the user clicks “login” open a popup window on a route that immediately triggers the Auth0 redirect.
  3. The user is redirected to Auth0 and logs in.
  4. Auth0 then redirects back to my site, we check for success, and set the isLoggedIn flag to a truthy value.
  5. The popup window can now close itself.
  6. Back in the main window, the local storage event listener is triggered, and we can use the Auth0 method getAccessTokenSilently to refresh the auth state.

We are now logged in inside the main window! There probably are other workarounds, but this is working fine for us, at least for now.


This approach requires you to configure Auth0 to cache using local storage and to enable refresh tokens. For React, that looks like this:

    redirect_uri: `${config.baseUrl}/callback`,


For local reproduction of this issue, I used Caddy as a reverse proxy, so I could conveniently add the headers to enable crossOriginIsolated:

# Caddyfile
:4200 {
  reverse_proxy localhost:4201 {
     header_down +Cross-Origin-Opener-Policy same-origin
     header_down +Cross-Origin-Embedder-Policy require-corp
  1. Start your React dev server, which in my case is running on port 4201.
  2. Start Caddy with caddy run.
  3. Go to localhost:4200.
  4. Open the dev tools console.
  5. Type crossOriginIsolated and hit enter: you will see it is true.
  6. Try using the loginWithPopup flow.

After entering your credentials within the “Universal Login” UI, the popup will just be a blank white screen. Open the dev tools for the popup window, and you should see the postMessage error from above.