MacOS Big Sur build 20A5354i

macOS Big Sur build 20A5354i is the official Beta 5 and second Public Beta build of macOS Big Sur, which was released to Apple developers on 19 August 2020. This build does not support the 27-inch iMac (Retina 5K, 27-inch, 2020). If you install this build on those Macs, you will encounter an error and you will have to reinstall macOS Catalina. It was also released as the second public beta on 20 August 2020.