How to know why Uniswap cancelled my transaction?

Question

I am not pro, but can someone check please why my transaction was cancelled on Ethereum after sending to Swap token on Uniswap v2?

https://etherscan.io/tx/0xbecb8ad0abc8459e378feed4c70740253436ee2d02df86a222e5cfea345c3d1f

Transaction is marked as failed and the only message I see is Warning! Error encountered during contract execution [execution reverted]

If I send eth_getTransactionReceipt RPC, I will not get any message error why it happened. Account has 33.43$. Transaction was about to buy token for 3.59$. Priority fee is more than base.

Full code:

base_fee_per_gas = w3.eth.gas_price   # baseFeePerGas in the latest block (in wei)
max_priority_fee_per_gas = w3.to_wei(1, 'gwei') # Priority fee to include the transaction in the block
max_fee_per_gas = base_fee_per_gas + int(0.5 * base_fee_per_gas) + max_priority_fee_per_gas # Maximum amount you’re willing to pay

buy_tx_params = {
    "nonce": w3.eth.get_transaction_count(account.address),
    "from": account.address,
    "chainId": 1,
    "gas": 500_000, # this I don't know how much to set up
    "maxPriorityFeePerGas": max_priority_fee_per_gas,
    "maxFeePerGas": max_fee_per_gas,
    "value": int(0.001 * 10**18), # 0.001 ETH
}

buy_path = [WETH_TOKEN_ADDRESS, UNISWAP_TOKEN_ADDRESS]

buy_tx = router_contract.functions.swapExactETHForTokens(
    0, # min amount out
    buy_path,
    account.address,
    int(time.time())+180 # deadline now + 180 sec
).build_transaction(buy_tx_params)

signed_buy_tx = w3.eth.account.sign_transaction(buy_tx, account.key)

Answer 1

No pair exists for the tokens in your path, it fails at calling getReserves on the pair, since the function doesn't exist there. You can try a tool like tenderly.co to easily analyse the revert point if verified. The second token being passed is a pair, I imagine the one you want to swap on.

Change this:

buy_path = [WETH_TOKEN_ADDRESS, UNISWAP_TOKEN_ADDRESS]

To:

buy_path = [WETH_TOKEN_ADDRESS, ELON_TOKEN_ADDRESS]

Simulation: