On Thursday 16th January at 7:03am UTC an update to our SSO service caused an issue that prevented some federated customers from logging in to our EU environment after successful authentication on their IdP. At 2:42pm UTC the problematic deployment was reverted, resolving the issue. We have introduced new testing to prevent a recurrence of this issue, and identified some process improvements and alerting changes to improve our response to incidents like this in the future.