error when running rosdep update

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Version Information:

ubuntu 16.04 ros Kinetic python-rosdep: Installed: 0.15.0-1 Candidate: 0.15.0-1 rosdep --version 0.15.0

Error:

ERROR: Not all sources were able to be updated.
[[[
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml]:
    Failed to download target platform data for gbpdistro:
    HTTP Error 503: Backend unavailable, connection timeout
]]]