Root Cause
The issue was caused by a database instance being unavailable due to a node failure. This led to a large number of open transactions, resulting in errors and preventing users from signing in.
Resolution
The affected node was recycled and restored, allowing users to log in again without further issues.
Action Plan
New alerts have been set up to monitor errors related to open transactions. Further investigation will be conducted to understand why these transactions were left open, and regular maintenance will be performed to prevent them from remaining unresolved.