BNB Chain Lagrange Testnet Upgrade: Key Details and Guidelines

The BNB Chain testnet is scheduled for a major upgrade, codenamed "Lagrange," at block height 7,841,000. This update introduces new features, optimizations, and critical fixes. Here’s what you need to know.

Introduction to the Lagrange Upgrade

Why Is It Named "Lagrange"?

The upgrade is named after Joseph-Louis Lagrange, a renowned mathematician and astronomer. His contributions to calculus, celestial mechanics, and physics—such as the Lagrange point and Lagrange mechanics—have left a lasting impact on science. This upgrade honors his legacy of innovation and precision.

Upgrade Type: Hard Fork

This is a hard fork upgrade, meaning it is not backward-compatible. Nodes must upgrade to the latest version to continue processing transactions and blocks. At least two-thirds of validator nodes must upgrade successfully for the network to function properly post-upgrade.

What Happens During the Upgrade?

At block height 7,841,000, the new rules take effect. Nodes that haven’t upgraded will be unable to process transactions or sync with the network.

Impact on Different User Groups

For BNB Holders

If you hold BNB on a supported exchange (e.g., Binance, Gate.io) or in a hardware wallet (e.g., Ledger), no action is required. Your funds are safe. However, it’s always good to confirm with your service provider.

For DEX Traders

The Binance DEX matching engine remains unchanged. Trading will continue as usual without interruptions.

For Full Node Operators

Node operators must upgrade to v0.8.1 before the target block height. Follow these steps:

Download the latest binary release.
Replace existing config.toml and app.toml files with the new versions (customize if needed).
Stop the current bnbchaind process and restart with:
```
bnbchaind start --home
```

What If I Miss the Upgrade?

Nodes that aren’t upgraded will fail to process transactions after the fork height. To recover:

Use the official state-recover tool to revert to block 7,840,999.
Backup your data directory.
Run:
```
./state_recover 7840999
```
Restart the node with v0.8.1.

👉 Explore detailed recovery steps

For Developers and SDK Users

If you use Go-SDK or Java-SDK, upgrade to the latest versions to support BEP82 and BEP87. Other SDKs may require code adjustments for compatibility.

Key Changes in the Upgrade

New Features

BEP82: Enables transfer of token ownership for BEP2 and BEP8 tokens. Token owners can assign new managers, and any user can burn tokens in their account.
BEP84: Simplifies token binding between BEP2 and BEP20 tokens. New mirror and sync methods ensure seamless cross-chain circulation.
BEP87: Reduces the minimum token symbol length from 3 to 2 characters.

Optimizations

Cross-chain transfers between BNB Chain and BSC are now more efficient and user-friendly.
Memo checks are enforced for cross-chain transfers. Transactions without memos will be automatically rejected to enhance security.

Bug Fixes

The underlying Tendermint and Cosmos-SDK frameworks have been updated to fix known issues and improve stability.

Client Updates

The new client version supports BEP82 and BEP87. Use tbnbcli to execute new commands, such as transferring token ownership:

./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

Frequently Asked Questions

What is a hard fork upgrade?
A hard fork is a permanent divergence from the previous version of the blockchain. Nodes must upgrade to continue participating in the network.

Do I need to move my BNB tokens?
No. If you hold BNB in a wallet or exchange, your tokens are safe. Only node operators and developers need to take action.

How does BEP84 improve token binding?
BEP84 introduces mirror and sync functions, making it easier to bind and synchronize BEP2 and BEP20 tokens across chains.

What happens if a cross-chain transfer has no memo?
It will be automatically rejected and refunded. Always include a memo for cross-chain transactions.

Can I create shorter token symbols after this upgrade?
Yes. BEP87 reduces the minimum symbol length to 2 characters.

Where can I get help if my node fails to upgrade?
Refer to the official documentation or community forums for technical support.

The Lagrange upgrade brings significant improvements to BNB Chain’s functionality and cross-chain capabilities. Node operators and developers should prioritize upgrading to avoid disruptions.

Stay informed about future updates by following official channels.