The Avalanche Bridge (AB) is a crucial tool for transferring ERC20 tokens between the Ethereum network and Avalanche's C-Chain. This comprehensive guide addresses the most common questions users have about its functionality, security, and operation.
Important Safety Information
To ensure the safety of your assets, it is critical to only interact with the Avalanche Bridge through its official user interface. Any deviation from this method can result in the permanent loss of funds. Below are specific actions that will lead to irreversible asset loss:
- Never send funds directly to any of the bridge's smart contract addresses. Transactions must be initiated through the official UI. Direct transfers to contract addresses are unrecoverable.
- Never send funds directly to any of the bridge's wallet addresses. All interactions must go through the approved web interface.
- Do not use smart contract wallets. The bridge is currently incompatible with smart contract wallets (e.g., Ambire, Argent, Gnosis Safe). Using one will result in the loss of funds, as these transactions cannot be processed or retrieved.
User Notes and Precautions
Before you begin, keep these practical tips in mind:
- MetaMask Mobile Bug: A known issue affects bridge transactions on the MetaMask mobile app. Until resolved, use the MetaMask desktop extension or the Coinbase Wallet app for mobile transfers.
- AVAX for Fees: You need AVAX, Avalanche's native token, to pay for transaction fees (gas) on the C-Chain. The bridge may airdrop a small amount of AVAX for qualifying transfers. Use this initial AVAX to swap for more on a decentralized exchange (DEX) to ensure you have enough for future transactions.
Understanding Bridge Transactions
How long does a bridge transfer take?
A transfer typically involves two steps. The Ethereum transaction usually takes 10-15 minutes to get the necessary confirmations. The Avalanche transaction is much faster, completing in a matter of seconds.
What can I do if my transaction seems stuck?
If your Ethereum transaction has no confirmations, you can use MetaMask's "Speed Up" feature to submit it with a higher gas price. If the Ethereum transaction has 35 confirmations but the interface appears stuck, check your wallet balance on the Avalanche network; the transfer is likely already complete. The UI may not update if you sped up the transaction.
Why is the Avalanche transaction part taking so long?
It isn't. The Avalanche portion only takes seconds. If the interface shows it taking longer, it is a display issue. Your assets have likely been transferred. Always verify your balance on the C-Chain explorer.
What if the gas price is more than the amount I am transferring?
If the Ethereum gas fee exceeds the value of your transfer, it is not economical to proceed. Wait for gas prices to decrease. For transfers to Ethereum, the bridge UI will prevent you from submitting a transfer value lower than the required fee.
Can I send tokens to a different address on the destination network?
No. The bridge only transfers assets to the same address on the other network. Once the assets arrive, you can then send them to any other address you control.
Can I speed up my transaction?
Yes, using MetaMask's "Speed Up" feature is safe for bridge transactions. It creates a new transaction with a higher gas price. Note that the bridge UI may not update to reflect this new transaction ID. After it gets 35 confirmations, check your Avalanche wallet balance.
Supported Assets and Functionality
What tokens can be transferred?
The bridge supports a specific list of ERC20 tokens created on Ethereum. On Avalanche, these tokens are represented with a .e suffix (e.g., USDT becomes USDT.e).
Can I send ETH or BTC?
The bridge does not support native ETH or BTC. You must first wrap them into their ERC20 equivalents (WETH or WBTC) on their native chain before bridging them.
Can I send tokens created on Avalanche to Ethereum?
Not currently. The bridge only supports moving Ethereum-based ERC20s to Avalanche and back. Support for Avalanche-originated tokens is planned for the future.
Can I send NFTs?
No, the Avalanche Bridge does not support NFT transfers.
I completed a transfer but don't see my tokens. What happened?
Your tokens are likely safe. Wallets like MetaMask need to be manually configured to "watch" for specific tokens. You must add the token's contract address to your wallet. The easiest way is to use the Proof of Assets page and click the MetaMask icon next to the token you need. 👉 Learn how to add custom tokens to your wallet
Why are there two versions of the same token (e.g., USDT and USDT.e)?
The .e tokens are from the current Avalanche Bridge (AB). A previous, now-deprecated bridge (AEB) created tokens without the suffix. For all new liquidity pools and dApp interactions, you should use the .e tokens. You can convert old AEB tokens to AB tokens using the official converter tool.
Fees and the AVAX Airdrop
How do bridge fees work?
The bridge charges a fee to cover network gas costs and operational expenses. Fees are paid "in-kind," meaning a portion of the token you are transferring is taken as payment.
- To Avalanche: A fixed fee of ~$3 worth of the transferred token.
- To Ethereum: A variable fee based on the current expected Ethereum gas cost, plus a ~$15 constant. This fee is highly variable and is displayed in the UI before you confirm.
Is there an AVAX airdrop?
Yes, to help users get started, the bridge airdrops a small amount of AVAX (up to 0.1 AVAX) when you transfer more than ~$75 worth of a token from Ethereum to Avalanche.
What if I didn't receive my airdrop?
First, confirm that your transfer value met the minimum requirement. If it did and you still did not receive it, you may need to contact support.
Security and Audits
Is the bridge trustless?
The bridge is designed to be trustless. No single party can access the collateral or mint assets. All transfers require approval from 3 out of 4 independent, reputable entities known as "Wardens."
Has the bridge been audited?
Yes, the entire bridge system, including its smart contracts and warden code, has been audited by the security firm Halborn. The audit reports are publicly available.
Troubleshooting and Support
My transaction isn't visible on the blockchain explorer.
It can take a few minutes for transactions to appear on explorers like Snowtrace (Avalanche) or Etherscan (Ethereum). Paste your wallet address into the relevant explorer to check. If you still cannot find it, seek support.
I can't see my funds. Are they lost forever?
It is highly unlikely your funds are lost. The most common issue is that the token is not visible in your wallet's UI because you haven't added it yet. The tokens are held on the blockchain, not in your wallet; your wallet is just a window to view them.
How can I contact support for help?
You can seek help on Avalanche's official support website or its Discord server. Before asking, please make a reasonable effort to search for your question, as it has likely been answered before.
Frequently Asked Questions
Q: What does the '.e' stand for in bridged tokens?
A: The '.e' suffix indicates that the token originated on the Ethereum network and was bridged to Avalanche using the Avalanche Bridge. It helps distinguish them from native Avalanche assets.
Q: Why won't my smart contract wallet work with the bridge?
A: The bridge's current technical architecture only supports transactions from Externally Owned Accounts (EOAs), like standard MetaMask wallets. Smart contracts cannot initiate transfers, so funds sent from them may be lost.
Q: How can I get AVAX to pay for fees if I don't have any?
A: If your initial bridge transfer is large enough, you will receive an AVAX airdrop. Otherwise, you can purchase AVAX on a centralized exchange and withdraw it to your C-Chain address, or use a fiat-on-ramp service within a supported wallet. 👉 Explore ways to acquire AVAX for transaction fees
Q: Can I bridge assets from other blockchains like BSC or Polygon?
A: Not directly. The AB only connects Ethereum and Avalanche. To move assets from another chain, you would typically bridge them to Ethereum first using another service, and then use the Avalanche Bridge to move them to Avalanche.
Q: Where can I trade my bridged tokens?
A: Bridged tokens (.e) can be traded on numerous decentralized exchanges (DEXs) within the Avalanche ecosystem, such as Pangolin and others.
Q: How do I set up MetaMask for Avalanche?
A: You need to add the Avalanche C-Chain network to your MetaMask wallet manually. This involves adding a new custom RPC network with specific details like the chain ID, RPC URL, and explorer. Official guides are available on the Avalanche support site.