neo@MacBook-Pro ~/ethereum/truffle/Conference % truffle migrate --reset
\Using network 'development'.

Running migration: 1_initial_conference.js
  Deploying Conference...
  ... undefined
Error encountered, bailing. Network state unknown. Review successful transactions manually.
Error: exceeds block gas limit
    at Object.InvalidResponse (/usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/errors.js:38:1)
    at /usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/requestmanager.js:86:1
    at /usr/local/lib/node_modules/truffle/build/webpack:/~/truffle-migrate/index.js:225:1
    at /usr/local/lib/node_modules/truffle/build/webpack:/~/truffle-provider/wrapper.js:134:1
    at XMLHttpRequest.request.onreadystatechange (/usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/httpprovider.js:128:1)
    at XMLHttpRequestEventTarget.dispatchEvent (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:64:1)
    at XMLHttpRequest._setReadyState (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:354:1)
    at XMLHttpRequest._onHttpResponseEnd (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:509:1)
    at IncomingMessage.<anonymous> (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:469:1)
    at IncomingMessage.emit (events.js:165:20)
		
		

		
neo@MacBook-Pro ~/ethereum/truffle/contracts % geth attach            
Welcome to the Geth JavaScript console!

instance: Geth/v1.8.1-stable/darwin-amd64/go1.10
coinbase: 0x5c18a33df2cc41a1beddc91133b8422e89f041b7
at block: 5381 (Wed, 28 Feb 2018 23:20:05 CST)
 datadir: /Users/neo/Library/Ethereum
 modules: admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

> web3.eth.getBlock("pending").gasLimit
4712388		
		
		

或者

		
$ truffle console
truffle(development)> web3.eth.getBlock("pending").gasLimit
6712390
		
		

修改 truffle.js 文件，加入 gas 值为上面所查询的值:

		
module.exports = {
  networks: {
    development: {
      host: "localhost",
      port: 8545,
      gas: 6712390,
      network_id: "*" // Match any network id
    }
  }
};