The Rails team has just released Rails 4.2.0.beta4.
In addition to the security fixes in 4.2.0.beta3, this new release includes a number of bug fixes for issues reported since the 4.2.0.beta2 release.
If all goes according to plan, this should be the last beta release for 4.2.0 before we move into the Release Candidates phase. We would like to thank all of the early adopters who participated in the beta testing and reported issues, as well as the 64 contributors who submitted patches to help our team address these bugs.
Happy upgrading!