Published on July 1, 2016. Updated on March 5, 2020. There are already quite a few guides in the wild to help with the upgrade of Rails 3.2 to Rails 4.0. The official Rails guide opens a new window for upgrading from Rails 3.2 to 4.0 is very thorough. With the recent release of Rails 5.0, apps currently in production running Rails 3.2 should probably be updated to any stable Rails 4 release as soo
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