ETHTransactionBuilder.autoFill Incorrect judgment of transaction type

[changlaoye]

When the "ETHTransactionType" value is not specified, on some EVM chains, calling the "_calculateEIP1559Fee" method in "ETHTransactionBuilder.autoFill" will invoke the "eth_feeHistory" RPC method, but the returned value will be 0. In "final fee = historical.toFee()", the "baseFee" value is 0, which leads to the transaction type being incorrectly identified as "EIP-1559".
This can be tested on the BSC chain.

[changlaoye]

Here is a testable blockchain RCP for your reference: https://mainnet.linksay.io

[mrtnetwork]

Here is a testable blockchain RCP for your reference: https://mainnet.linksay.io

Hi, I don’t think this is a plugin bug. Some RPC providers expose newer APIs even for chains that do not support EIP-1559.

In practice, reliably detecting whether a chain supports EIP-1559 is tricky. I’ve run into this many times:

eth_feeHistory may be implemented and return data even on non-1559 chains

The presence of that RPC alone is not a reliable signal

Scanning recent transactions to check whether the transaction type is 0x02 (EIP-1559) or legacy (0x0) is usually more reliable, but this breaks down on local or low-activity test nodes.

Because of these inconsistencies, the safest approach is to require the transaction type to be explicitly specified, rather than trying to auto-detect the protocol upgrade from RPC responses.

Unfortunately, there is no fully reliable way to detect EIP-1559 support purely via RPC, since some nodes return feeHistory without actually enforcing 1559 rules.

[changlaoye]

Can we determine if 'fee.baseFee' is equal to 0 by using "final fee = historical.toFee();"? If it's equal to 0, then it's at least not EIP-1559.

Alternatively, we can use the RPC method "eth_getBlockByNumber" to get the latest block information and check if "baseFeePerGas" is equal to 0. If it's 0, then it's at least not EIP-1559.

[mrtnetwork]

Can we determine if 'fee.baseFee' is equal to 0 by using "final fee = historical.toFee();"? If it's equal to 0, then it's at least not EIP-1559.

Alternatively, we can use the RPC method "eth_getBlockByNumber" to get the latest block information and check if "baseFeePerGas" is equal to 0. If it's 0, then it's at least not EIP-1559.

i will check that