A family statement released through his publicists says Miller died Friday and there are no further details available on how he died.
Miller, who also drew headlines for his two-year relationship with singer Ariana Grande that ended earlier this year, was apparently found dead at his home in Los Angeles.
After the breakup, Grande tweeted: "pls take care of yourself."
Los Angeles police said they responded to a report of a deceased person at a home on the same block where Miller is listed as a resident, but released no other details.
McCormick's last tweet was posted on 6:45 p.m. Thursday about his upcoming tour, set to begin in October.
While Miller didn't have a hit on Top 40 radio, he had a strong following on streaming networks. He often alluded to his battles with addiction over the years.
Some information from the Associated Press.
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