SharePoint Online: Unexpected errors accessing files

We are continuing to investigate this issue.

We continue to work with Microsoft on understanding the impact and cause of the issue we are experiencing. So far there has been no indication that there is a systemic issue across the Microsoft platform, and it appears isolated to Cardiff only.

We have also been made aware that some users of the Business Intelligence (BI) service may not be able to access the BI site as this is hosted on SharePoint (https://cf.sharepoint.com/sites/bi/SitePages/BI-Home.aspx).

There is still no confirmed mitigation or workaround to this issue so far, but some users have reported success in using a private/incognito session in web browser.

We have been made aware of a number of reports of people not being able to access files within various Microsoft Teams spaces or SharePoint sites that they expect to have access to.
We are working with Microsoft support to better understand the issue and work towards a resolution, but do not have a timescale for this yet.

There is no confirmed workaround identified at this time, but using a private/incognito session on a web browser can help to avoid issues with cookies.