Users can’t access SharePoint Online sites and receive an authentication error

Title: Users can’t access SharePoint Online sites and receive an authentication error
User impact: Users may be unable to access SharePoint Online sites and receive an authentication error.
Current status: Additional investigation revealed that impact stemmed from a code issue introduced in a recent update intended to optimize the code path leveraged for users’ sign-ins. As previously mentioned, we corrected this code issue, and were continuing to see positive trends as a result of our mitigative efforts. We’re continuing to monitor for a period to ensure the positive trajectory continues and also to validate that no additional remediation actions are required to provide relief for all users.
Scope of impact: Your organization is affected by this event, and some users attempting to access SharePoint Online sites may be impacted.
Start time: Wednesday, February 7, 2024, at 1:00 AM UTC
Root cause: A recent update intended to optimize the code path leveraged for users’ sign-ins introduced a code issue, resulting in impact.
Next update by: Thursday, February 8, 2024, at 9:30 PM UTC