The frat bros behind The Chainsmokers’ ASU gig — yeah, the one cops rolled up on this previous weekend — are telling TMZ it was chaos from the soar … ‘trigger even getting the bash up and working was a manic last-minute scramble.

The president of ASU’s Phi Gamma Delta — AKA FIJI — chapter and fellow board members inform TMZ the primary home they locked in for the gig straight-up failed, due to a plumbing catastrophe that flooded the yard days earlier than … so that they needed to haul all of the gear out and pivot quick.

They inform us it was so last-minute, the occasion wasn’t even formally confirmed till 16 hours out — and to prime it off, cops had been already on the scene earlier than the social gathering had even began.

As for the positive the cops slapped on them, they verify to TMZ that The Chainsmokers’ Alex Pall and Drew Taggart are selecting up the tab for the quotation — and the fraternity is severely grateful, because it may’ve set them again wherever from $1,000 to $2,500.

Regardless of all of the chaos, Jonas McAllister — who arrange the celeb campus cameo by means of his work at a reserving firm — tells us all of it got here collectively in the long run, and they’d positively do it once more.