Halsey said an asthma attack wrecked her BottleRock set over the weekend, forcing her to seek treatment by the medics after her performance, USA Today noted.
Taking to Twitter, the 23-year-old singer explained that she had the asthma attack while on stage performing at the Napa Valley festival Sunday.
"This is what I get for walking the mile in high school gym class," she quipped, making light of the situation.
Halsey remained upbeat about the saga, posting a follow-up tweet saying she had fun performing at BottleRock despite the heat and asthma attack.
The "Bad at Love" singer may have been apologetic about her performance, which she felt was less-than-par, however fans flooded social media with words of encouragement and support.
"I could barely tell. hope you feel better," one Twitter user said.
"I loved this set so much," another person posted.
The annual BottleRock Festival over the Memorial Day weekend also featured artists such as The Killers, Muse and Bruno Mars, who recently bagged several awards at the 2018 Billboard Music Awards.