HDFC Bank has announced that its UPI service will be unavailable on November 5 and November 23 due to essential system maintenance. On November 5, the service will be down from 12:00 AM to 2:00 AM, while on November 23, it will be unavailable from 12:00 AM to 3:00 AM. This outage will affect all financial and non-financial UPI transactions for HDFC Bank customers.