Zayn Malik pulled out of a show at the last minute due to the "worst anxiety of my career".
The former One Direction star was due to appear at Capital's Summertime Ball at Wembley Arena on Saturday night, but didn't make it.
Someone had to take to the stage at the event to announce Malik would not be performing, saying "we're all absolutely devastated...this is truly out of our hands, we are really sorry".
Malik took to Twitter to explain himself to his fans, who were heard booing and expressing their upset in the crowd.
He wrote: "Unfortunately my anxiety that has haunted me throughout the last few months around live performances has gotten the better of me.
"With the magnitude of the event, I have suffered the worst anxiety of my career. I cannot apologise enough but I want to be honest with everyone who has patiently waited to see me, I promise I will do my best to make this up to everybody I've let down today.
"I know those who suffer anxiety will understand and I hope those who don't can empathise with my situation."
Fans and fellow celebs flocked to Twitter to express their concern and support for the star, and praised his bravery in being honest.
@zaynmalik get well soon Zayn. We can understand. Just do what you gotta do to feel better. Ignore those haters, we're all here for you. xx— Zayn Malik Updates (@OfficialWithZJM) June 12, 2016
Anxiety is real... I know the feeling https://t.co/Tt18LZJWsU— Ellie Goulding (@elliegoulding) June 12, 2016
To @zaynmalik and anyone else that deals with anxiety, you're never a disappointment to your fans or yourself. You're stronger than you know— CelebMix (@CelebMix) June 11, 2016
@zaynmalik Take your time, get yourself feeling better, everyone can wait. Good & brave decision made today.— Rae Earl (@RaeEarl) June 11, 2016