Failed to read the 'sessionStorage' property from 'Window': Access is denied for this document.

We are using @auth0/auth0-spa-js 1.12.0 and recently see errors like this one:

Error: Failed to read the 'sessionStorage' property from 'Window': Access is denied for this document.
      at Object.get (node_modules/@auth0/auth0-spa-js/dist/../src/storage.ts:88:18)
      at new e2 (node_modules/@auth0/auth0-spa-js/dist/../src/transaction-manager.ts:18:36)
      at new e2 (node_modules/@auth0/auth0-spa-js/dist/../src/Auth0Client.ts:155:30)
      at init6 (packages/lib.web.auth/index.ts:81:20)
      ...

Because of this error, it is not possible to create a Auth0Client instance and therefore the affected users can not authenticate.

Unfortunately we were not able to reproduce the error yet. All we know is, that the userAgent is always “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36 Edg/85.0.564.70” indicating an Edge 85 browser running on Windows 10.

[AK-047]

It’s still not working with an iframe and blocked third-party cookies. Is there any way to force client initialization to use memory storage or something else to avoid this issue?

[norbertschuler]

Just for information: If you have third party cookies disabled in Chrome and include a website using auth0-spa-js in an iframe, this error also occurs. Not for the same website if you directly view it in the browser without putting it into an iframe.