I'm seeing the same thing. I found some other website mention using these Terminal commands to bypass the Wi-Fi requriement:
defaults write com.apple.NetworkBrowser BrowseAllInterfaces 1
but unfortunately we still get the "canceled the copy" messages immediately after one person accepts the copy.
I have exactly the same problem between a 2011 iMac and a 2011 Macbook Air. Both systems running 10.7.3.
Interestingly, I can transfer from the air to the imac, but not the reverse.
I don't know if this is important but only the imac is connected to the internet (via ethernet). Both computers have wifi on (of course!)
So I spoke to Apple Support about the problem. Turns out my ethernet connection was interfering with the AirDrop. When I removed the ethernet cable from the iMac, AirDrop would work as normal. The support person said it shouldn't happen and he was going to look into it further, but if you are having this problem, try removing the ethernet cable from the offending computer, if there is one connected.
Same issue and same work-around fixed issue for me too. I looked in it further in the Network preferences pane of both the macs and came to the following conclusion:
*On both the macs, WiFi is #1 under Set Service Order and Ethernet is at #2.
*iMac->Air: file from iMac to MacBook Air.
*Network Preferences pane - order of the network interfaces on left hand column.
Test Scenarios for AirDrop from an iMac to a MacBook Air, both on 10.8 and eligible for AirDrop:
1. iMac->Air (on iMac - WiFi with no IP, yellow dot, and above unplugged Ethernet, red dot) & (on Air - any order of Ethernet and WiFi): success
2. iMac->Air (on iMac - Ethernet with valid IP, green dot, and above WiFi with no IP, yellow dot) (on Air - any order of Ethernet and WiFi): no go
CONCLUSION: For AirDrop to work with Ethernet connected and valid Ethernet IP Address, on the Network Preferences pane on the left-hand interface cloumn, we need to have WiFi above Ethernet. the only way to do this is to have a valid IP Address for Wifi and set the service order for WiFi priority, which can be done as follows:
::System Preferences -> Network -> unlock padlock -> click the gear (3rd button) below list of interfaces -> Set Service Order -> Drag Wifi to the top (or drag the one at top towards bottom till WiFi comes to the top) ->click "Ok" -> click "Apply".
BOTTOM LINE: WiFi needs to be #1 (above Ethernet) in the list of network interfaces for AirDrop to send a file with Ethernet connected and with an IP address. The receiving computer can have any order of network interface.
So, if the Ethernet has a valid IP Address, the only way WiFi will be above Ethernet is if there is a valid IP address for WiFi as well and the WiFi is set as the primary interface in Set Service Order option.
guys, let me know if I am not accurate..
In my case I got the "cancelled the copy" message because there wasn't enough storage room on my Air to accommodate the folder I wanted to transfer. I had no idea what was going on and thought it was a networking issue. It's stupid, but I thought I'd mention it. Be nice if instead of the ambiguous "canceled" message you got the standard "not enough room" message.