Can’t access an online word document in another tenant.

The issue seems to be with the cached credentials for that tenant not being updated on login. Microsoft’s support instructed to recreate user profile or reinstall PC.

According to https://www.sharepointpro.com.au/blog/outlook-error-1001-microsoft-365-fix/ and https://learn.microsoft.com/en-us/answers/questions/5652240/error-message-(7anyj) Perform the following steps.

  1. Log out of office apps
  2. Delete cached credentials from the Credential Manager
  3. Delete all files and folders inside %localappdata%\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy
  4. Delete C:\Users\yourusername\AppData\Local\Microsoft\OneAuth and C:\Users\yourusername\AppData\Local\Microsoft\IdentityCache
  5. Repair Office because I deleted too many things and I couldn’t log back in.

After that it worked.