This pop-up window saying iCloud won't work until I free up space is unclickable, I tried clicking both buttons, but nothing happened. I can drag it around with my mouse, but no other interaction. (I currently have 400 MB free of 128 GB HDD)
MacBook Air, macOS High Sierra (10.13)
Can you access the Finder to empty your Trash and remove some large files? You should free at least 10GB of storage; 400MB is critically low.
Connect an external drive and move some large files to the external drive.
Can you get access to a different computer? Borrow another Mac from a friend or family member and connect your computer in target Disk mode. The other computer will see your Mac as an external drive and you can try to move videos or music, or photos to an external drive. https://support.apple.com/hr-hr/HT201462
What happens when you try to access Finder? Can you click on the Desktop to get the Finder as the foremost application and then use command - N to open a new Finder window?
I'm unable to open Finder or Trash. I can open Storage Management, but not from that pop-up. In Storage management it says that "System" is using 90 GB, so I don't know what that means (as shown in the picture). I also can't open Finder to move files to an external drive.
Why iCloud pop-up won't go away
