Edite / usr / bin / do-release-upgrade e comente as linhas 123 - 127
# make sure to inform the user if his distro is no longer supported
# this will make it appear in motd (that calls do-release-upgrade in
# check-new-release mode)
# if m.no_longer_supported is not None:
# url = "http://www.ubuntu.com/releaseendoflife"
# print(_("Your Ubuntu release is not supported anymore."))
# print(_("For upgrade information, please visit:\n"
# "%(url)s\n") % { 'url' : url })
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