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UHVPN Client compatibility with Mac Lion

How to use the built in VPN on Mac 10.7


The current version of the Cisco VPN Client does not appear to run properly if Mac OS is running the 64-bit kernel. Mac OS 10.7/Lion runs the 64-bit kernel by default. Users will see the error "Error 51: Unable to communicate with the VPN subsystem" when starting the VPN. Until Cisco releases a compatible client, there are a few workarounds available:

  • Set Mac OS X to boot using the 32-bit kernel according to the instructions in Apple's support article
  • Configure the Mac OS X built-in VPN client to connect to the UH VPN using the PDF instructions:

Please note that this issue is not specific to Mac OS 10.7/Lion. Apple has a list of Macs that use the 64-bit kernel by default as well as instructions to find out if you're using 64-bit mode.


Mac OS-X 10.7 / Lion

page last updated: November 19, 2013
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