The AnyConnect package on the secure gateway could not be located. You may be experiencing network connectivity issues. Please try connecting again.
The above error message was received after installing anyconnect-macosx-i386-2.5.1025-k9.dmg on a Mac Pro 3,1 running OS X 10.6.4. Using Wireshark to monitor the en2 interface on the Mac Pro, I see that it establishes a connection on port 443 to the ASA 5540 gateway.
The cypher exchange appears to complete successfully and both systems begin exchanging data. The bulk of the data is being transmitted by the ASA 5540. After the ASA transmits packet 34 in the session, the Mac Pro transmits an Encrypted Alert (packet 35) to the ASA 5540. Packet 36 is a FIN ACK packet from the Mac Pro closing the connection.