Blink-182 bassist Mark Hoppus' public announcement about his cancer treatment was actually an accident.

Hoppus took the internet by surprise when he posted a photo of him receiving chemotherapy to his Instagram story in June. The musician told GQ magazine that the post was actually an accident, and he had meant to only share it using the "close friends" feature on Instagram.

Mark Hoppus of Blink-182 performs during the "Linkin Park & Friends Celebrate Life in Honor of Chester Bennington" concert at Hollywood Bowl in Los Angeles, California, U.S., October 27, 2017. Picture taken October 27. REUTERS/Mario Anzuoni

Mark Hoppus revealed his original cancer diagnosis announcement was actually an accident. (REUTERS/Mario Anzuoni)

"Throughout the day as I'm getting chemotherapy and more bags of chemicals are being dripped into my body, other people are reaching out, and they're like, ‘Dude, what's going on?’" Hoppus said during an interview with the outlet.

Hoppus was quickly contacted by his manager asking if the musician had meant to post the news. Shortly after, Hoppus began receiving messages from friends and family he hadn't told yet. However, he couldn't respond to the messages due to the chemotherapy.

BLINK-182 BASSIST MARK HOPPUS SAYS HE'S ‘CANCER FREE’

Hoppus had shared a photo of himself preparing for a round of chemotherapy to his Instagram story instead of to just his "close friends" list on the app.

Hoppus had shared a photo of himself preparing for a round of chemotherapy to his Instagram story instead of to just his "close friends" list on the app. (Kevin Mazur/Getty Images for iHeartMedia)

"Chemo is like being on the worst international, overnight flight where you can't sleep or get comfortable," he told GQ.

Later that day, Hoppus wrote out a formal statement that he shared on social media.

"For the past three months I've been undergoing chemotherapy for cancer," he wrote at the time. "I have cancer. It sucks, and I'm scared, and at the same time I'm blessed with incredible doctors and family and friends to get me through this."

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Hoppus had been diagnosed with an aggressive blood cancer, stage 4 diffuse large B-cell lymphoma.

Hoppus revealed he went through a dark time after finding out about his diagnosis. The musician used therapy to help get through the first weeks after finding out the news.

"I had a really dark time after finding out," he told GQ.

Hoppus announced he is cancer-free in September.

Hoppus announced he is cancer-free in September. (Jeff Kravitz/FilmMagic for iHeartMedia)

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"I went through this whole period of like, not why me, but of course me. Why wouldn't it be me? We've had so much good luck and good fortune, and things have kind of fallen into place for me specifically for so long, that of course I was due. I was due for something tragic."

Hoppus is now cancer-free.

"Just saw my oncologist, and I’m cancer free!!" the Blink-182 rocker wrote in an Instagram post in September. "Thank you, God and universe and friends and family and everyone who sent support and kindness and love."