The 2022 Rogers outage that left 12 million people without wireless and hard-wired services was caused by human error and made worse by management and system “deficiencies,” says an independent review conducted for Canada’s telecommunications regulator.

The 26-hour outage started early in the early morning of July 8 and left individuals and businesses without access to their mobile, home phone, internet and 911 services.

Staff at Rogers caused the shutdown, the report says, by removing a control filter that directed information to its appropriate destination.

Without the filter in place, a flood of information was sent into Rogers’ core network, overloading and crashing the system within minutes of the control filter being removed.

Designating risks in phase six as “low” meant Rogers’ staff could avoid additional levels of scrutiny and approvals as the upgrade proceeded, even though doing so “contravenes industry norms,” the report says.