External user access to the SharePoint Online library - howto

Dorje-McKinnon 

I've had a few issues with this way of sharing entire sharepoint online libraries.

But they almost always boil down to a user getting one of two error messages:

• That didn't work
  We're sorry, but <user email> can't be found in the <your company>.sharepoint.com directory
  Issue Type: User not in directory.
• Sorry, you don't have access. Then a message box, and a "Request access" button

In almost every case the issue has been the user has multiple email accounts associated with Microsoft accounts, and or browser cache of credentials.

The simple fix (8 hours to find this simple fix) is to get the user who is seeing these errors to go back to the email they got from you titled : “<person name> is inviting you to collaborate on <library name>” , right click on the OPEN button , select copy link, open an incognito / private or inPrivate browser window and paste in the OPEN button url. They are then prompted to login , ensure they use the email address you shared the library to, and 90% of the time they will get access.

Hopefully this helps everyone.

and right click on the