The Binance Chain Testnet is expected to have a scheduled hard fork upgrade at block height 7,841,000. Based on the current block generation speed, it is forecasted to be around 2021/01/21 at 5:00 AM (UTC). The full node runners on testnet are expected to switch their software version to v0.8.1 by 2021/01/21. Binance Chain Mainnet will also be undergoing an upgrade a few weeks later (please stay tuned with the future announcement).

1. Background Story

1.1 Who is Joseph-Louis Lagrange?

This upgrade is named after Joseph-Louis Lagrange in honor of his key significant contributions to the fields of analysis, number theory, and both classical and celestial mechanics. Several concepts from mathematics and physics are named after him.

1.2 What is a hardfork upgrade?

A hardfork is an upgrade that is not compatible with the previous release because some breaking changes are introduced in the latest release. A hardfork in Binance Chain requires +⅔ validators to successfully upgrade to keep making blocks. If the existing full nodes in the network do not upgrade, they will not be able to receive and execute further blocks normally after the hardfork block height.

1.3 What happens during a network upgrade?

Logic changes will occur at block height 7,841,000 for this upgrade. After the activation of the upgrade, the blockchain is able to handle a series of new business logic.

2. How does this upgrade affect me?

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

If you use any exchanges which support BNB (such as Binance.com, BitMax or Gate.io), one of the [wallets](https://docs.binance.org/wallets.html), or a hardware wallet (such as Ledger, Cool Wallet), you do not need to do anything unless your exchange or wallet service specifies otherwise.

2.2 As a Binance  DEX user, what do I have to do?

There are no changes to Binance DEX matching engine logic. You do not need to do anything.

2.3 As a fullnode operator, what do I have to do?

This release is breaking and you need to switch to v0.8.1 . Upgrade instructions are (all the below should be done before the hardfork block height:

1. If your node is already synced with the network, please download the new v0.8.1 testnet binary and replace the previous version

2. Replace the config.toml and app.toml under home folder with the latest versions. You can customize those parameters.

3. Stop the bnbchaind process and restart it with v0.8.1.

bnbchaind start --home <home-path>

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

If you cannot upgrade your software, you cannot sync with the upgraded Binance Chain peer/validator nodes. You will not be able to connect or send transactions.

How to recover?

Detailed can be found at the doc-site

1. Download the tool state-recover from node-binary repo for fixing the upgrade issue

2. Backup your home directory

3. Since the height of the upgrade is set to be 7,841,000, you can run the following command to recover the state to just one block before the upgrade, which is 7,840,999 :

./state_recover 7840999 <your_home_path>

4. Restart with the version v0.8.1 of bnbchaind

bnbchaind start --home <home-path>

2.5 As a Binance Chain wallet provider or service consumer, what do I have to do?

If you are a wallet provider, please pay attention to the changes in the new functions for

BEP82 and BEP87 :

• Go-SDK: https://github.com/binance-chain/go-sdk/releases/tag/v1.2.6
• Java-SDK: https://github.com/binance-chain/java-sdk/releases/tag/v1.1.1
  

3. Upcoming Changes

3.1 What will be changed with the blockchain feature?

3.1.1 New Features of Binance Chain node:

• Introducing BEP82 to allow token ownership change

BEP82 allows increased flexibility of BEP2&BEP8 token management. Token issuers can renounce their ownership and promote others. This BEP also allows token holders to burn their tokens.

• Introducing BEP84 to enable a simplified token binding process

BEP84 proposes two new permissionless methods that will be imported into TokenManager contract

Mirror: If a BEP20 contract is not bound to any BEP2 token, anyone can call the mirror method to automatically issue a BEP2 token and bind them.

Sync: For a BEP20 token that has been mirrored to BC, anyone can call the sync method to balance the total supply on BC and BSC.

• Introducing BEP87 to allow shorter token symbol length

BEP87 changes the minimal symbol length to 2. Previously, the length of the symbol for representing an asset is between 3 and 8. Now the length can be as short as 2.

3.1.2 Improvements

• Cross-chain Transfer Improvements

Some modifications and edge cases get addressed to enable a faster and less error-prone process.

• Enable account scripts for cross-chain transfer

BEP12 was introduced to check whether the memo field of any transfer transaction is empty. In the new release, the memo of cross-chain transfer is also checked. From now on, the deposit transaction without memo to exchanges be returned automatically.

3.1.3 Bug Fix

The latest Binance Chain release includes all the critical bug fixes from Cosmos-SDK and Tendermint repositories.

3.2   New Features of Binance Chain Client:

Release of Binance Chain Client with BEP82 and  BEP87 Support: You can now use tbnbcli to change token owner.

./tbnbcli token transfer-ownership --from  $current-owner --symbol $symbol --new-owner $new-owner --chain-id Binance-Chain-Nile  --node=data-seed-pre-2-s1.binance.org:80--trust-node

Thanks for your cooperation, and let’s make Binance DEX a modern and secure marketplace for issuing and exchanging digital assets

Binance Chain Community

2021/01/19

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