在Aave借贷操作中触发Gas估算失败的ValueError问题求助

我正在学习DeFi与Aave相关内容，在执行借贷操作时遇到以下错误：

ValueError: Gas estimation failed: 'The execution failed due to an exception.'. This transaction will likely revert. If you wish to broadcast, you must set the gas limit manually.

最初以为是资金不足，但增加账户资金并将借贷金额设为极低值后，问题仍未解决。其中deposit功能正常，仅borrow操作触发上述错误。

相关代码 #

def main():
    account = get_account()
    erc20_address = config["networks"][network.show_active()]["weth_token"]

    if network.show_active() in ["mainnet-fork"]:
        get_weth()

    lending_pool = get_lending_pool()
    print(lending_pool)

    # 授权ERC20代币转账
    approve_erc20(amount, lending_pool.address, erc20_address, account)

    tx = lending_pool.deposit(
        erc20_address, amount, account.address, 0, {"from": account}
    )
    tx.wait(1)
    print("存款成功!!!")
    borrowable_eth, total_debt = get_borrowable_data(lending_pool, account)
    print("开始借贷!!")

    dai_eth_price_feed = config["networks"][network.show_active()]["dai_eth_price_feed"]
    dai_eth_price = get_asset_price(dai_eth_price_feed)

    amount_dai_to_borrow = (borrowable_eth * 0.05) / dai_eth_price

    print(
        f"准备借贷 {amount_dai_to_borrow} DAI ({Web3.toWei(borrowable_eth*0.05, 'ether')} wei)"
    )

    dai_address = config["networks"][network.show_active()]["dai_token"]

    borrow_tx = lending_pool.borrow(
        dai_address,
        Web3.toWei(amount_dai_to_borrow, "ether"),
        1,
        0,
        account.address,
        {"from": account},
    )

    borrow_tx.wait(1)
    print("已借到DAI")

brownie-config.yaml配置 #

dependencies:
  - aave/protocol-v2@1.0.1
compiler:
  solc:
    remappings:
      - '@aave=aave/protocol-v2@1.0.1'

networks:
  default: mainnet-fork
  kovan:
    weth_token: '0xd0A1E359811322d97991E03f863a0C30C2cF029C'
    lending_pool_addresses_provider: '0x88757f2f99175387ab4c6a4b3067c77a695b0349'
    dai_eth_price_feed: '0x22B58f1EbEDfCA50feF632bD73368b2FdA96D541'
    dai_token: '0x4F96Fe3b7A6Cf9725f59d353F723c1bDb64CA6Aa'
  mainnet-fork:
    weth_token: '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2'
    lending_pool_addresses_provider: '0xB53C1a33016B2DC2fF3653530bfF1848a515c8c5'
    dai_eth_price_feed: '0x773616E4d11A78F511299002da57A0a94577F1f4'
    dai_token: '0x6B175474E89094C44Da98b954EedeAC495271d0F'
dotenv: .env
wallets:
  from_key: ${PRIVATE_KEY}

排查方向与解决建议 #

1. 利率模式参数错误
   borrow函数第三个参数为利率模式，你当前传的是1（变量利率模式）。部分资产在特定网络可能不支持该模式，可尝试改为2（稳定利率模式）测试，或查阅Aave官方文档确认DAI支持的利率模式。

2. 借贷金额精度问题
   计算amount_dai_to_borrow时可能出现精度丢失，导致实际金额不符合Aave最小借贷要求。建议先固定小额借贷（比如Web3.toWei(1, "ether")），排除计算逻辑问题。

3. 可借贷储备不足
   即使是fork环境，也可能出现DAI可借贷储备为0的情况。可调用lending_pool.getReserveData(dai_address)查看availableLiquidity字段，确认是否有可借额度。

4. 合约实例正确性
   检查get_lending_pool()函数是否正确通过配置中的lending_pool_addresses_provider调用getLendingPool()方法，确保返回的是Aave V2 Lending Pool的有效合约实例。

修改示例代码 #

# 调整borrow参数，固定借贷金额+切换利率模式
borrow_tx = lending_pool.borrow(
    dai_address,
    Web3.toWei(1, "ether"),  # 固定借1DAI测试
    2,  # 使用稳定利率模式
    0,
    account.address,
    {"from": account},
)

内容的提问来源于stack exchange，提问作者Irfan wani