From ruby developers, they announced Ruby 1.9.3 has ended.
https://www.ruby-lang.org/en/news/2015/02/23/support-for-ruby-1-9-3-has-ended/
td-agent 1, old stable, uses Ruby 1.9.3.
td-agent 1's bundled Ruby is never updated if the company maintains the Ruby 1.9.3.
td-agent 2, current stable, uses Ruby 2.1.x so there is no impact.
We continue to provide td-agent 1 for exsiting users with updating bundled gems
but we recommend to use td-agent 2 for new deployment.
Thanks,
Masahiro