External Users: Randomly Access Denied

Question

I have a number of external users in an external users' permissions group, which has access to a specific library in a larger site. They don't have access to the full site. For most users this works perfectly, but some users get the following error:

Access Denied [...] does not have permissions to access this resource. [...] Issue Type: User does not have permissions.

I've checked permissions comparing an external user whose access works and a user whose access doesn't. They have the same permissions at both the resource (contribute), and site (limited access). We've tried deleting the broken account wholly via Power Shell and re-creating it, but no dice.

This is SharePoint Online.

Answer 1

Please check which account accepted the SharePoint Online invitation for certain external user.

Navigate to user information list as below, click the broken external users name and check their email address

http://siteurl/_layouts/15/people.aspx?MembershipGroupId=0

An article about issue when an external user accepts a SharePoint Online invitation by using another account and how to resolve it.

And go to Office 365 admin center->Users->Guest users, make sure the external users appear in this list.