I am writing a proof of concept using truffle and testrpc and I have to spend hours optimizing the code to avoid out of gas errors. Is there a way to bypass this error or have a very high value. I have tried setting high limit on testrpc

testrpc -l 4500000000000

Tried specifying high gas in truffle.js

networks: {
    development: {
      host: "",
      port: 8545,
      network_id: "*" // Match any network id
      ,gas: 500000000

But still, encounter out of gas when running my tests.

Transaction: 0x0981ab4c4ebdcb851e138d7a18344d256489ef01259f6b714edefdfe23ab824c
  Contract created: 0xccb7c4bd42c1e8e809d9f4573a2c2e0590b27b78
  Gas usage: 500000000
  Block Number: 23
  Block Time: Tue Jan 16 2018 08:35:30 GMT-0800 (PST)
  Runtime Error: out of gas

If I comment out 5 lines of the code triggering events (for validation failures), it runs without any issues with the default 6.7M gas. Here are my events, I have switched to bytes32 from string.

// Used for error handling.
  event AnyException(bytes32 m);
  event AnyException(bytes32 m1, bytes32 m2);
  event AnyException(bytes32 m1, bytes32 m2, bytes32 m3);

Here is a successful transaction after commenting 5 lines generating events using default gas in truffle.js.

Transaction: 0xb9f0f703c7f7e1ae5d51fc8170c00d2f12de146c6c2d5b48a47bd2a1e2a14203
  Contract created: 0x87d84cf9d012a181658ce76fa03ab1a7bc0ad538
  Gas usage: 6227032
  Block Number: 28
  Block Time: Tue Jan 16 2018 08:51:03 GMT-0800 (PST)

How can gas usage jump so high with 5 lines of event logs?

3 Answers 3


The gas limit you set up in testrpc is different than the gas limit for transactions from your client. The testrpc configuration is used to specify a limit for blocks on the blockchain. However, the gas limit used when creating a contract is going to be either the value set in the gas field in your transaction object, or if you don't provide one, it will make a call to estimateGas(). I have seen cases in testrpc where estimateGas() returns a bad estimate resulting in a low gas limit used for that transaction causing out of gas errors. Make sure you're specifying a gas limit in your client when sending the transaction and you should (hopefully) see this error go away.

  • Thanks, Adam. I understand that truffle uses fixed gas for testrpc. From the error message, I can see it uses 500000000 gas which is specified in truffle.js.
    – Titu
    Jan 22, 2018 at 16:22

It helped me when I added solc optimizer to truffle.js and ran

truffle compile --all


module.exports = {
  // See <http://truffleframework.com/docs/advanced/configuration>
  // for more about customizing your Truffle configuration!
  networks: {
    development: {
      host: "",
      port: 8545,
      network_id: "*" // Match any network id
  solc: { optimizer: { enabled: true, runs: 200 } }


TestRPC 3.0.0 Breaking Changes: Default gas limit for transactions is now 90000 gas instead of the full block gas limit.

To avoid these new out of gas errors, you can now pass a higher gas limit as a parameter to web3:

web3.eth.sendTransaction({..., gas: 3141592}) // choose your own gas limit suitable for you

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