Microsoft's Central India Azure region was hit by an overnight outage, disrupting services across the country.

Lasting from around 12:41 UTC on 18 May 2020 to 08:30 UTC on 19 May 2020, the incident was blamed on a grid failure, and subsequent issues with air handling units.

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Azure India Outage
– Azure Status Page

"A power issue with the regional utility power provider caused a Central India data center to transfer to generator power," Microsoft said on its status page.

"This transition to generators worked as designed for all infrastructure systems except for a number of air handling units in two of the data center's internal zones (Colos). As a result, internal temperatures for these two Colos rose above operational thresholds, alerts were triggered, and automation began shutting down network and storage resources to protect data."

With the storage scale units offline, this impacted virtual machines and any other Azure service that relied on the systems.

"Engineers undertook various workstreams to bring back connectivity," Microsoft said.

"First, technicians isolated the unhealthy air handling units and restored power, returning temperatures to operational levels. Once temperatures were below threshold, technicians started to physically recover Storage scale units. With Storage and Networking restored, dependent Compute scale units began to recover. As Compute nodes became healthy, reliant Virtual Machines and other dependent Azure services also recovered."

Among those impacted by the outage were payment processing companies PayU and Citrus Pay, both of which were inundated with complaints about their services no longer working.

The Azure data center is located in Pune, in the western Indian state of Maharashtra. The company promised to provide a more detailed analysis of the incident within three days.