I've used Migration Assistant to move my old user account from Windows to Mac. After a while the disk on my Mac being full. Now the Mac won't startup

I've tried to enter in Safe mode, but it doesn't start. I've tried from Recovery mode>Terminal but there is follow error: no space left on device.

I haven't another Mac, only a PC.

How I can access to Mac disk and delete some files?

2 Answers 2


The first thing to do is backup your data, although if you were migrating from the PC to the Mac, then you've probably already got an original copy there anyway.

If you have a backup, then probably the easiest thing to do is create a bootable external drive, boot your Mac up from that, and then delete files from the internal drive.

If you have an external USB hard drive, you can start up from macOS Recovery to format it and install macOS. More specifically, you have the following macOS Recovery options:

  • commandR to reinstall the latest macOS that was installed on your Mac, without upgrading to a later version
  • optioncommandR to upgrade to the latest macOS that is compatible with your Mac
  • shiftoptioncommandR to reinstall the macOS that came with your Mac, or the version closest to it that is still available

Broadly speaking, follow these steps:

  1. Boot up into macOS Recovery using one of the options above
  2. Use the Disk Utility option to erase/format the external USB drive (NOTE: This means you will lose all data on it. Another option is to use a USB Thumb Drive of at least 8GB in size, although this will probably be a lot slower).
  3. Once it's formatted, install macOS. (This will take a while).
  4. Once complete, boot up from the external drive by holding the option key during startup and then selecting it to boot off.
  5. Once booted up into macOS from your external drive, your Mac's internal drive should be accessible as if it's an external drive.
  6. Delete files from the internal drive. (Note: You will want to ensure you have at least about 9GB of free space in order for macOS to function properly. However, my recommendation is that you generally was to have no less than about 15% of your drive's capacity free).
  7. Make sure you don't forget to empty the Trash (Finder > Empty Trash...)
  8. When you've freed up enough space, go to Apple > System Preferences > Startup Disk and make sure you've selected the internal drive as your startup disk
  9. Shut Down your Mac (Apple > Shut Down...)

Barring any other issues, you should now be able to boot up from your internal drive.

  • I would add to the answer that you should "edit" the backed up files to make sure you are not transferring GB of temporary files , log files that you may not have seen or read etc etc Oh and do check that the size of what you want to transfer is smaller than the space available including the effect of 15% as suggested.
    – Solar Mike
    Commented Dec 3, 2017 at 8:50
  • After booting from USB drive with High Sierra Installer, i see my internal hd, but when i attempt to delete some files appear the follow message: "No left space on device".
    – Premier
    Commented Dec 3, 2017 at 15:20
  • Just to clarify, are you booting from an external drive that macOS is installed on, or from a macOS installer?
    – Monomeeth
    Commented Dec 3, 2017 at 20:53

There might be a simpler way just boot off your mac to single user mode by holding CMD+S at start-up chime hold it till you see plain text then type mount -uw then type cd /Users/homedirectoryname/. Then suppose you want to delete a file in desktop named cat.txt then type rm -R desktop/cat.txt and and if you want to delete a file named John folder which has spaces then the path to the folder will be John\ folder. It is actually a bit tuff but all the best. And if you want to delete all the png or jpg files in a folder . Then type /Folder/*.png and if you are wondering what * is it means all the files under a directory so when you type *.png or *.jpg it means delete all the files with extension .png. Same applies for any extension. Oh after finishing type exit this will boot to your system.

  • It doesn't work, when i attempt to delete a file it says "No space left on device"
    – Premier
    Commented Dec 3, 2017 at 15:31

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