I have an iMac and I'm trying to use the folder /Users/Shared to share files between different users of that iMac. When I copy something large to that folder two things happen

  • The iMac slows down a lot
  • On a macbook that I also own (same network, logged into same iCloud account, ...) there is a popup "pasting X items from iMac" and it seems to initiate a copy over the network

What is this? Why is copying to the /Users/Shared folder initiating a network copy, and to where?

File Sharing (and all other sharing options) are disabled on both the iMac and the Macbook.


This isn't anything specific to the Shared folder, but rather because you're using the clipboard to copy files there.

When you copy something such that it is placed on the clipboard, Universal Clipboard allows those files to be pasted anywhere across any of your devices logged into the same iCloud account, including iOS devices and Macs.

To disable this functionality, disable Handoff in System Preferences → General → Allow Handoff between this Mac and your iCloud devices.

macOS Sierra: Copy and paste across devices

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  • Yes, this could be. But why does the copy start even if no paste action was initiated on the Macbook (it does, I just checked). I also checked that it has nothing to do with the "Shared" folder, pointing to universal clipboard. This is quite idiotic behaviour. – Thomas Dec 31 '17 at 12:49
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    @Thomas The copy is initiated on all ‘active’ devices, so if you're using two Macs at once they will both sync clipboards. The copy won't be initiated if the other Mac is sleeping, which it should be if you're not actively using it. In my opinion, Universal Clipboard is one of the most useful features of Sierra :) – grg Dec 31 '17 at 12:52
  • Yes, I use Universal Clipboard all the time but I'm very confused about this auto paste. Here is a question: On the mac that is not sleeping and not being interacted with, WHERE does it paste those 50 GB? What if that mac runs out of disk space? – Thomas Dec 31 '17 at 13:08
  • Another issue is that you never know which mac is sleeping and which mac is doing a power nap. So this explains the "Your disk is full" messages that I saw once on my Macbook after copying some stuff around on the iMac. I think it is a design flaw that files are transferred already on the copy and not at the paste. – Thomas Dec 31 '17 at 20:33

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