which service gave you the error. Can you invoke the UI at port 8000?
If you can – proceed with the tutorials ignoring the error.
later you can make a note of the error and troubleshoot in Ambari.
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if you are saying that you vm does not boot at all — it is likely a networking configuration issue — though i haven’t seen that with virtualbox.
check this
http://hortonworks.com/community/forums/topic/ip-address-in-virtual-box-points-to-127-0-0-18888/
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p.s. i am using vmware not virtualbox