Ubuntu’s previous spring release, 14.04 LTS, went live on April 17, 2014.
As with all releases post-13.04, Ubuntu proper only makes fleeting appearances in select milestone releases, specifically the ‘final beta’ and the ‘release candidate’ stages.
Ubuntu’s family of flavours, which may include Ubuntu MATE this cycle, take full advantage of the testing opportunities at hand.
- Alpha 1 – December 18th (for flavours)
- Alpha 2 – January 22nd (for flavours)
- Feature Freeze — February 19th
- Beta 1 – February 28th (for flavours)
- UI Freeze — March 12th
- Final Beta – March 26th
- Kernel Freeze — April 9th
- Release Candidate – April 16th
- Ubuntu 15.04 Final – April 23rd
[Source: OMG! Ubuntu!]