Delta Air Lines sued CrowdStrike on Friday, claiming the cybersecurity company cut corners and caused a global technology outage that led to the cancellation of thousands of flights in July.

The airline is seeking compensation and punitive damages for the outage, which began with a faulty update sent to several million Microsoft computers. Delta said the outage paralyzed its operations for several days, costing more than $500 million in lost revenue and additional expenses.

CrowdStrike said Delta gives “false information,” doesn’t understand cybersecurity and is trying to shift blame for its slow recovery from the outage.

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The U.S. Department of Transportation is investigating why Delta has taken longer to recover than other carriers. Transportation Secretary Pete Buttigieg said the department would also look into complaints about Delta’s customer service during the outage, including long waits for help and reports that unaccompanied minors were stranded at airports.

In its lawsuit, Delta claims the outage occurred because CrowdStrike failed to test the update before rolling it out globally.

Delta canceled about 7,000 flights over a five-day period during the peak summer vacation season. The outage also affected banks, hospitals and other businesses.

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“CrowdStrike caused a global catastrophe because it cut corners, took shortcuts, and circumvented the announced testing and certification processes, for its own benefit and profit,” Delta said in the lawsuit filed before the Superior Court of Fulton County Georgia. near the company’s headquarters.

A CrowdStrike spokesperson said the company attempted to resolve the dispute. One of its lawyers said in August that CrowdStrike’s liability to Delta was less than $10 million.

The spokesperson said Delta’s claims are based on “disinformation, demonstrate a lack of understanding of how modern cybersecurity works, and reflect a desperate attempt to blame its slow recovery on its failure to modernize its infrastructure.” obsolete IT.