Today we release Cardano 1.5 on the Cardano testnet in preparation for the later release to the mainnet. The Cardano 1.5 release is a milestone because it is the last Cardano release of the Byron development phase, which we have been in since the launch of mainnet.

Cardano 1.5 is important in preparation for moving to the Shelley development phase. This update brings a new consensus protocol, Ouroboros BFT, which is a key step in the transition from Ouroboros Classic, the current consensus protocol running the Cardano network, to Ouroboros Genesis, the protocol for the Shelley era. Ouroboros Genesis is a major upgrade to the protocol that underpins Cardano because it is 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 1.5 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 is technically a hard fork but will take place in a smooth and automatic way because this is a planned protocol upgrade whereby all parties of the current federated system have agreed to the change.

Anyone running a Cardano version before 1.5 will not be able to make the hard fork. Users of the Cardano testnet are strongly encouraged to upgrade to 1.5 to help the development team test the transition on the testnet before we make Cardano 1.5 release on the mainnet. When the 1.5 release is made later on the mainnet, users will be able to easily upgrade by following prompts in Daedalus.

Cryptocurrency exchanges that have still not migrated from v0 to v1 of the wallet API should do so now. We encourage exchanges to use this testnet release to test their integration with the v1 API. The v0 wallet API, which was deprecated in the 1.4 release, is now completely removed in the 1.5 release and can no longer be used.

The Cardano 1.5 release also makes many other improvements. These include 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.