From the alpha 6 ship list twbs/bootstrap#20939

• New flexbox column classes - (conflict with auto prop value) Add support for column class which automatically sizes flexbox columns twbs/bootstrap#20963
• Tag renamed back to Badge Rename .tag to .badge to avoid conflicting with WordPress twbs/bootstrap#21020
• .in and .active to .show - https://github.com/twbs/bootstrap/pull/20982/files Rename .active to .show twbs/bootstrap#21036
  • affects the following: Alert, Collapse, Dropdown, Modal, Popover, Tooltips
  • now could be a good time to switch isOpen to isActive across the library
  • ^ it might be possible to support both props in the next version vs doing that in current version
• .row .no-gutters Add .no-gutters option to remove gutters from rows twbs/bootstrap#21211
• Progress bar rewritten v4: Rewrite progress component without <progress> element twbs/bootstrap#21473
• Fix navbars and navs

Also, I think it's time to ship alpha releases that keep up with changes in twbs/bootstrap#master for people keeping up with latest. Also need to get #195 out to help with this.

reactstrap v4 prerelease

We'll be using the v4 branch to prioritize bootstrap breaking changes. Prerelease versions are now published to npm under the next tag and their respective prerelease version.