BNB Beacon Chain Testnet First Sunset Upgrade Announcement

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The BNB Beacon Chain testnet is expected to have a scheduled hard fork upgrade at block height 50,121,232. Based on the current block generation speed, the hard fork is forecasted to occur on 4th March 2024. at 6:00 (UTC). The full node runners on testnet must switch their software version to v0.10.17 by 4th March.

1. Background Story

1.1 What is the First Sunset Upgrade?

The BNB Chain Fusion represents a strategic shift, integrating the Beacon Chain’s features into the BNB Smart Chain (BSC) and phasing out the former.  This move aims to streamline the network, improve efficiency, reduce security risks, and align BNB Chain’s architecture with the current technological demands and future growth. BEP333  proposes to securely and smoothly transit the BNB Beacon Chain and BSC from a dual-chain structure into a single chain structure and decommission the Beacon Chain. This 3-phase approach begins with the first sunset upgrade, marking the initial step towards the BC Fusion milestone.

1.2 What is a hard fork?

A hard fork is an upgrade that is incompatible with the previous release because some breaking changes are introduced in the latest release. A hard fork in BNB Beacon Chain requires 2⁄3 of validators to upgrade to make blocks successfully. If the existing full nodes in the network do not upgrade, they will not receive and execute further blocks after the hard fork block height.

1.3 What happens during a network upgrade?

New rules and logic changes will occur for this upgrade at block height of 50,121,232. After the upgrade kicks in, the blockchain can handle a series of new business rules and logic.

2. How does this upgrade affect me?

2.1 As a BNB/BEP2 holder, what do I have to do?

Following the BC Fusion, accessing assets on the BNB Beacon Chain will become significantly difficult, if not impossible. To aid digital asset issuers and holders on the BNB Beacon Chain, this guide provides comprehensive instructions for transferring the value of assets such as BEP2/BEP8 tokens, both prior to and subsequent to the Beacon Chain Fusion. 

Here is an outline of all important milestones in the BNB Chain Fusion roadmap, set to facilitate a smooth transition for the BNB Chain community.

2.2 As a full node operator, what do I have to do?

This is a hard fork release, and you need to switch to v0.10.17. Upgrade instructions are as below (you should do all the below before the hard fork block height):

  1. If your node is already synced with the network, please download the new v0.10.17 binary and replace the previous version, and download the new config file app.toml to replace the previous version or add FirstSunsetHeight = 50121232 under the [upgrade] module of app.toml.
  2. Stop the bnbchaind process and restart it with  v0.10.17.

2.4 What will happen if I forget to upgrade my full node in time?

If you fail to upgrade your software on time, your node will not sync with the upgraded BNB Beacon Chain peer/validator nodes. You will not be able to connect or send transactions.

How to recover?

You can find detailed info at doc-site.

  1. Download the tool state-recover from release for fixing the upgrade issue
  2. Backup your home directory

Since the height of the upgrade is set to be 50,121,232, you can run the following command to recover the state to just one block before the upgrade, which is 50,121,231:

./state_recover 50121231 <your_home_path>
  1. Restart with the version v0.10.17 of bnbchaind
bnbchaind start –home <home-path>

3. Upcoming Changes

3.1 What will change with the blockchain feature?

HTLT and asset lock impacts

Due to the requirement of returning cryptocurrency to the user’s wallet in order to migrate funds to BSC through BEP-299. The Beacon Chain will disable specific types of transactions to encourage users to keep their funds in their own wallets. The following types of Beacon chain transactions will be disabled: TimeLockMsgTimeRelockMsgFreezeMsgIssueMsgMintMsgIssueMiniMsgHTLTMsgDepositHTLTMsg.

This move will effectively disable the Hashed Timelock Contract (HTLT) feature, which is pivotal for facilitating atomic swaps between the Beacon Chain and other chains. By doing so, it also implies that atomic swaps, a mechanism allowing for the exchange of cryptocurrencies across different blockchains without the need for a trusted third party, will no longer be supported on the Beacon Chain.

Disabling these transactions also means that time lock-related transactions will be ceased. Time lock transactions are used to lock assets until a specified future time or until certain conditions are met. This feature is crucial for various DeFi applications, including those that require assets to be locked as part of staking, liquidity provision, or other smart contract-based mechanisms.

Validator management Impacts

After the upgrade, the Beacon Chain will restrict the creation and modification of validators to avoid conflicts with validators established on the BSC side. Additionally, new delegations will not be permitted. The Beacon Chain will disable transactions including: MsgCreateValidatorOpenMsgCreateSideChainValidatorMsgCreateSideChainValidatorWithVoteAddrMsgEditSideChainValidatorWithVoteAddrMsgSideChainDelegateMsgSideChainReDelegate.

3.2 What will be different for users?

There will be no difference for users of BNB Beacon Chain.

Thanks for your cooperation, and let’s make the BNB Beacon Chain a modern and secure infrastructure for the BNB ecosystem.

BNB Beacon Chain Community

Forum: Build N Build



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