Getting "ValueError: intrinsic gas too low" when trying to make a basic swap on Quickswap (polygon/matic)

Question

I'm using Brownie to try and make a basic swap on Quickswap:

from brownie import accounts, config, network, interface


def main():
    """
    Runs the make_swap function on the Uniswap pair address for two particular tokens, wbtc & weth
    """
    make_swap()


def make_swap():
    """
    swap two particular tokens, wbtc and weth 
    """
    usdc = interface.WmaticInterface(config["networks"][network.show_active()]["usdc"])
    weth = interface.WmaticInterface(config["networks"][network.show_active()]["weth"])
    router = interface.IUniswapV2Router02(config["networks"][network.show_active()]["quickswap_router_v2_02"])

    acct = accounts.add(
        config["wallets"]["from_key"]
    )  # add your keystore ID as an argument to this call
    amountIn = 0.5*10**usdc.decimals()
    usdc.approve(router, amountIn, {"from": acct})
    amountOutMin = 0.000383501*0.5*10**weth.decimals() #checked this from external source - quickswap
    path = [usdc, weth]
    deadline = 3000
    tx = router.swapExactTokensForTokens(amountIn, amountOutMin, path, acct, deadline, {"from": acct, "allow_revert": True})
    print("Swap made!")
    return tx
    

The approve part goes through fine, but the actual swap gets reverted with the 'intrinsic gas too low' error:

    Brownie v1.14.6 - Python development framework for Ethereum

AaveFlashloanProject is the active project.

Running 'scripts/make_swap.py::main'...
Transaction sent: 0x8900880fa866f02dcde13eedffbb862c3fa8fcc6444078e159136984146fed94
  Gas price: 1.0 gwei   Gas limit: 50098   Nonce: 13
  WmaticInterface.approve confirmed - Block: 14979417   Gas used: 38198 (76.25%)

  File "brownie/_cli/run.py", line 49, in main
    return_value, frame = run(
  File "brownie/project/scripts.py", line 103, in run
    return_value = f_locals[method_name](*args, **kwargs)
  File "./scripts/make_swap.py", line 8, in main
    make_swap()
  File "./scripts/make_swap.py", line 27, in make_swap
    tx = router.swapExactTokensForTokens(amountIn, amountOutMin, path, acct, deadline, {"from": acct, "allow_revert": True})
  File "brownie/network/contract.py", line 1676, in __call__
    return self.transact(*args)
  File "brownie/network/contract.py", line 1550, in transact
    return tx["from"].transfer(
  File "brownie/network/account.py", line 615, in transfer
    exc = VirtualMachineError(e)
  File "brownie/exceptions.py", line 85, in __init__
    raise ValueError(exc["message"]) from None
ValueError: intrinsic gas too low

Here are my gas parameters from the brownie config file:

live:
gas_limit: auto
gas_buffer: 1.1
gas_price: auto
reverting_tx_gas_limit: true
default_contract_owner: false

I've tried adjusting gas limit to max, and gas_price to max, but doesn't seem to help.

Any ideas how to solve? And does Polygon even charge an intrinsic gas fee? I've looked on the block explorer and it looks like most similar transactions to this do go through with a gas price of 1...

Answer 1

Solved it. It was the deadline parameter - all I did was increase it from 3000 to something like 11111111, and the thing went through straight away.

I'm now noticing that I get this 'intrinsic gas too low' error quite a lot for a wide range of different errors - for example, when I hadn't approved the uniswap router to spend my tokens, it gave me the 'intrinsic gas too low' error. Would love to know if anyone knows why it gives that error in so many circumstances??