
Microsoft Exchange admin portal is currently inaccessible from some browsers after Microsoft forgot to renew the SSL certificate for the website. Microsoft Exchange admins who accessed the admin portal at admin.exchange.microsoft.com suddenly found that their browsers were issuing warnings that the connection was not private due to an expired SSL certificate.
Users are blocked from accessing the site as a security precaution or shown an alert that the data may not be secure.

Expired SSL certificate for admin.exchange.microosft.com
Microsoft states that they are aware of the issue and are working on a fix. As a temporary workaround, Microsoft states you can access the admin portal from the https://outlook.office.com/ecp/ URL as well.
Outages caused by expired certificates are becoming all too common as almost all online services have now switched over to secure connections.null
With encrypted communications come additional complexity and human error, such as forgetting to renew an SSL certificate. We have also seen expired SSL certificates affecting consumer-facing services, such as Spotify, Microsoft Teams, and Facebook’s Tor server.