Newbe Dev Stack

Answer : Okay, the solution is that I did not disable Time Machine and remove all backup drives first. Doing that solved the issue. So the full solution is: Disable "Backup Up Automatically" in Time Machine System Preferences, and remove all backup drives, such that it looks like this: Then run sudo tmutil thinlocalsnapshots / 999999999999 And try again. Optionally restart the computer and try again. In Mojave, what I had to do was turn off Time Machine and then run this command to force clean out the local snapshots: tmutil thinlocalsnapshots / 1000000000 1 where 1000000000 is the size of your drive and the "1" means urgent. This has to be done a few times since it only cleans up a few local snapshots each time. After that, you should be able to see sufficient space available with this command: diskutil apfs resizecontainer disk0s2 limits Open activity monitor and force quit backupd , then click continue in the bootcamp assistant.

Answer : I was experiencing this problem after downloading High Sierra to fix a friend's Mac. I found Rick's solution worked for me, but I've added a few more steps. Click the  symbol in the Menu bar. Click Restart…. Hold down Command + R to boot into Recovery Mode. Click Utilities. Select Terminal. Type csrutil disable . This will disable SIP. Press Return or Enter on your keyboard. Click the  symbol in the Menu bar. Click Restart…. Extra Steps Log in / boot up the Mac. Empty Trash. I also found that somehow Previous System folder appeared under the Mac HD. So I also trashed that (which wouldn't trash previously). I then rebooted the Mac a few times to check that everything was working fine. Then rebooted into recovery mode. Hold down Command + R to reboot into Recovery Mode. Click Utilities. Select Terminal. Type csrutil enable . This will enable SIP. Press Return or Enter on your keyboard. Click the  symbol in the Menu bar. C...