"What do you use in place of DiskWarrior to repair data for APFS?"に関する回答Catalina, together with the APFS file structure, has been a NIGHTMARE. I assume that you have run Disk Utility from an external drive, the restore partition (command-R boot) or an internet boot (command-option-R)? If so, what error messages did you receive, if any? If the drive passes the Disk Utility testing, there is probably a software issue and you can reinstall the OS from the restore partition or an internet boot. HOWEVER, if this occurred IMMEDIATELY following an attempt to install Catalina chances are the install and accompanying restructuring of the drive went sideways and you will probably never get it to run correctly again without reinitializing the drive (APFS) and doing a clean reinstall of the OS. This has been our experience in the office dealing with a LOT of these systems in an area where the internet connections are sub-standard at best.