I am trying to update my MacBook to new macOS Catalina. But my downloading had failed twice. Now I downloaded installer but I can't update because I have low disk space. Because when my download was failed 1 and 2 time my disk space is not clear. How to fix it? How to clean updates folder with ?
My update failled mid-way and is stuck. Spend 7 hours at Apple store. Seems to do with purgeable storage. Catalina will only install if it has enough free storage. Purgeable memory does not count. To turn purgable storage to free storage disable iCloud and Time Machine backups among other techniques.
I had the same problem and solved booting the system in secure mode (hold shift during boot).
macOS High Sierra (10.13) or later have an APFS file system which does disk state snapshots which are accessible as Time Machine backup.
That means what in case of restart loop because of lack of free space you need to boot into recovery mode by holding Cmd + R right after machine starts, and go into Restore from Time Machine Backup there: you will have local time machine backups and will be able to restore system to its state just before the upgrade.
You don't need an external disk with Time Machine copy to do that, APFS does this for you automatically.
Deleting a file from APFS from recovery mode would not free any disk space because of the snapshot system, mentioned above.