This was Intentional

The NSA, despite being ordered by a judge to preserve records because of a lawsuit, deleted all of the records:

The National Security Agency destroyed surveillance data it pledged to preserve in connection with pending lawsuits and apparently never took some of the steps it told a federal court it had taken to make sure the information wasn’t destroyed, according to recent court filings.

Word of the NSA’s foul-up is emerging just as Congress has extended for six years the legal authority the agency uses for much of its surveillance work conducted through U.S. internet providers and tech firms. President Donald Trump signed that measure into law Friday.

Since 2007, the NSA has been under court orders to preserve data about certain of its surveillance efforts that came under legal attack following disclosures that President George W. Bush ordered warrantless wiretapping of international communications after the 2001 terrorist attacks on the U.S. In addition, the agency has made a series of representations in court over the years about how it is complying with its duties.

However, the NSA told U.S. District Court Judge Jeffrey White in a filing on Thursday night and another little-noticed submission last year that the agency did not preserve the content of internet communications intercepted between 2001 and 2007 under the program Bush ordered. To make matters worse, backup tapes that might have mitigated the failure were erased in 2009, 2011 and 2016, the NSA said.

This is a repeated behavior, and it was repeated over and over again, from an organization that throws away nothing, ever.

This was a deliberate action that was conducted to cover up misconduct by the organization. 

The only question is how high in the chain of command that it went.