Essentially the question is how to set/change the "minimal cost of the transaction" a.k.a. "Gtransaction" value using Parity?

On a private blockchain with a custom chain spec file I have a minGasLimit of 0x9c4. I used to think this means that the gas has to be at least 2500 (decimal)

But when I try to make a transaction by setting 4000 gas, I get this error:

Transaction gas is too low. There is not enough gas to cover minimal cost of the transaction (minimal: 21000, got: 4000). Try increasing supplied gas.

I searched the chain spec file(s) for "5208" because that is the hex representation of 21000. But it's not in the file.

As @benjaminion points out, this 21000 is the Gtransaction value in Appendix G of the Yellowpaper (http://yellowpaper.io/).

So I have two specific questions:

  1. Does Parity allow the ability to change the 21000 Gtransaction default? If so, what value must I edit?

  2. What actually does minGasLimit refer to in the Parity chain spec, since it is obviously not the "Gtransaction" a.k.a. "minimal cost of transaction"? A Yellowpaper reference would be ideal.

EDIT: I just found this about the geth genesis file, and it seems to say that gasLimit is the correct term for configuring Gtransaction in the gensis file. But like I say in the beginning, I have edited this value on my Parity chain spec but the 21000 number keeps coming up. Here is the geth reference:


  • I think minGasLimit is something else - probably the minimum block gas limit that miners can vote it down to, on my reading of the Chain Spec. A transaction will always use at least 21000 gas since that is the value specified in the protocol: it is the quantity G_transaction in the Yellow Paper, appendix G. Commented Oct 7, 2017 at 18:29
  • @benjaminion I have edited my question with your commend in mind. Parity allows changing a lot of things geth doesn't, and one question I have is how to affect the Gtransaction value you pointed me to. The other question is what minGasLimit actually means, if not Gtransaction. Thank you.
    – stone.212
    Commented Oct 8, 2017 at 0:59
  • @benjaminion You said "A transaction will always use at least 21000 gas" but the "gasLimit" in the genesis file for mainnet is "0x1388" which means 5000. So... something seems off, right?
    – stone.212
    Commented Oct 8, 2017 at 22:52


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