Cardano SL 3.0.0
Overview
Cardano SL 3.0.0 (of Cardano 1.5.0 release) provides a new consensus protocol, Ouroboros BFT, that is important in preparation for moving to the Shelley phase. Ouroboros BFT is a key step in the transition from Ouroboros Classic, the current consensus protocol running the Cardano network in Byron era, to Ouroboros Genesis, the protocol for the Shelley era. (Ouroboros Genesis will be a major upgrade to the protocol that underpins Cardano because it is the first proof-of-stake protocol that matches the security guarantees of proof-of-work protocols such as Bitcoin.)
Ouroboros BFT will not be immediately activated after deployment of the release. It will be activated through a protocol update later, which will be announced separately. This protocol update will deactivate the Ouroboros Classic protocol and activate the Ouroboros BFT consensus protocol. This update will be, technically. a hard fork; it will take place in a smooth and automatic way as a planned protocol upgrade whereby all parties of the current federated system will have agreed to the change.
The v0 wallet API, which was deprecated in Cardano SL 2.0.0 (of Cardano 1.4.0 release), is now completely removed in Cardano SL 3.0.0 and can no longer be used. Therefore cryptocurrency exchanges need to migrate from v0 to v1 wallet API before upgrading to this release.
This release also includes many other improvements like performance improvements when rendering lists with a large number of transactions and wallet addresses, the addition of features for detecting insufficient disk space, and a new screen that visualizes the block storage consolidation process.
For more information please see the release notes.
Release notes
Support portal
Cardano versioning
https://iohk.io/blog/how-cardano-releases-are-versioned/