My MacBook Pro system disc is full, but I can't delete any files OR empty the trash to
how can I find more space when I cannot delete anything (says error)
MacBook Pro 15″, macOS 10.13
Question marked as
When using macOS 10.13+ with the new APFS file system it is possible to encounter a situation where you cannot delete any files. This happens due to how the APFS file system works. APFS must first write new data to the file system before being able to remove the old data (including metadata). So you now have the classic chicken and egg problem common with CoW (Copy on Write) file systems unless the file system makes sure to reserve a small amount of space to prevent this situation which Apple obviously does not do properly.
You can try to thin or delete any APFS snapshots (I'm not sure if it is possible in this state or not):
If not, then you may want to reboot into Internet Recovery Mode using Command + Option + R to see you thin or delete the APFS snapshots.
Otherwise you will need to erase the whole physical drive before reinstalling macOS or restoring from a backup you made before this issue occurred.