Hash Sum mismatch while update package index(indigo/ubuntu 14.04.04)

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This is usually a temporary issue, and happens when you download packages at the same time that a repository sync is happening. It should go away if you try again a few minutes later.

Are you using an HTTP proxy?

Update

This error means that the checksum on the Packages file ( http://packages.ros.org/ros/ubuntu/di... ) doesn't match the checksum that is listed in the Release file ( http://packages.ros.org/ros/ubuntu/di... ). I guess you could download both files and try to manually verify the checksums.

When I compute the checksums on the Packages file, I get:

$ wget http://packages.ros.org/ros/ubuntu/dists/trusty/main/binary-amd64/Packages
$ sha1sum Packages 
058296435aba9ad217d436d338c9a19a37e0df74  Packages
$ md5sum Packages 
e8f069b226d4fa7155e90ef02f3235ec  Packages

And these match the checksums listed in the Release file (these checksums will be out of date in a few days, so be sure to check against the most recent copy of the Release file, and not the checksums listed here).