Equinix has blamed a significant outage at its Singapore data center on a third party contractor.

A contractor "incorrectly sent a signal to close the valves from the chilled water buffer tanks," Business Times reports.

The signal was sent during a planned system upgrade. "This raised the temperatures in some of the halls in the data center and impacted some customer’s operations," an Equinix spokesperson said.

The October 14 outage brought down banking services of DBS and Citibank in Singapore, and caused issues with Facebook, Instagram, WhatsApp, and Call of Duty in the Philippines, Hong Kong, and India.

The Monetary Authority of Singapore (MAS) has told both banks to conduct a thorough investigation into why their backup data centers were not able to bring systems back within a short time frame.

"No IT system is infallible," MAS said in a statement. "Banks and customers should have contingency measures in the event of service disruptions caused by IT outages."