A Chinese cryptocurrency creator who bid $4.57 million to have lunch with legendary investor Warren Buffett says he’s had to postpone the meal. Justin Sun was due to sit down with Buffett, a noted cryptocurrency skeptic, on Thursday after winning a charity auction last month. But Sun had to reschedule after coming down with kidney stones, his blockchain organization TRON Foundation said on Twitter Monday. “Parties agreed to reschedule at a later date,” the group added. Sun said in a post Tuesday on Chinese social network Weibo that he was recovering in the hospital. Sun created a cryptocurrency called TRX token in 2017 and has been a longtime advocate of the industry. Buffett, on the other hand, has long been wary of digital currencies. The Berkshire Hathaway\n \n (BRKA) CEO once called bitcoin “rat poison,” and predicted that investing in cryptocurrencies would result in “bad endings.” In June, Sun said in an open letter that he viewed the lunch as an opportunity “to bridge the divide between the blockchain industry and traditional investors.” To that end, he wrote, he planned to invite several industry leaders to the event “to aid in the conversation and support the overall cryptocurrency and blockchain community.” “I also firmly believe that with the right communication and understanding, Buffett will change his overall stance on cryptocurrency and blockchain, allowing this new investment strategy to become integrated into his overall portfolio,” Sun added. The lunch was originally scheduled to be held this Thursday at Quince, a Michelin-starred restaurant in San Francisco, according to the TRON Foundation. The proceeds raised from Sun’s auction bid were set to go to Glide, a Bay Area nonprofit dedicated to helping people deal with poverty, homelessness and substance abuse issues. Buffett has been a longtime supporter of Glide, offering to have lunch with the highest bidder at the annual auction for 20 years. Sun said on Weibo that “the donation to the Glide Foundation has been completed and it is still valid.” A representative for Buffett did not immediately respond to a request for comment outside regular business hours.