I initalised a new truffle project by using truffle init.

I changed the solc version to ^0.6.0 in the truffle-config.js file.

I ran truffle compile and got this error:

TypeError: Error parsing C:/init-truffle/contracts/Migrations.sol: Cannot read property 'addFunction' of undefined
    at runWithReadCallback (C:\Users\Lino\AppData\Roaming\npm\node_modules\truffle\build\webpack:\~\solc\wrapper.js:37:1)
    at compileStandard (C:\Users\Lino\AppData\Roaming\npm\node_modules\truffle\build\webpack:\~\solc\wrapper.js:78:1)
    at Object.compileStandardWrapper (C:\Users\Lino\AppData\Roaming\npm\node_modules\truffle\build\webpack:\~\solc\wrapper.js:85:1)
    at Object.parseImports (C:\Users\Lino\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\truffle-compile\parser.js:47:1)
    at Object.getImports (C:\Users\Lino\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\truffle-compile\profiler.js:374:1)
    at Promise.all.then.results (C:\Users\Lino\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\truffle-compile\profiler.js:346:1)
Truffle v5.0.5 (core: 5.0.5)
Node v10.16.3

Here is the Migration.sol file:

pragma solidity >=0.4.21 <0.7.0;

contract Migrations {
  address public owner;
  uint public last_completed_migration;

  constructor() public {
    owner = msg.sender;

  modifier restricted() {
    if (msg.sender == owner) _;

  function setCompleted(uint completed) public restricted {
    last_completed_migration = completed;

Here is the 1_initial_migration.js file:

const Migrations = artifacts.require("Migrations");

module.exports = function(deployer) {

Does anyone know what to do? This file compile without any problems with solc version set to ^0.5.0.


  • Operating System: Windows 10
  • Truffle v5.0.5 (core: 5.0.5)
  • Node v10.16.3


  • This seems to be a problem from your JS code. please add your JS/Web3js code.
    – Masoud jt
    Jun 19, 2020 at 13:54
  • I added the only JS file automatically created by Truffle when running truffle init I modified noting more than the solidity compiler version, so there is no web3js code. Jun 19, 2020 at 14:15
  • Could be an issue with Truffle which you can report at github.com/trufflesuite/truffle/issues. Jun 20, 2020 at 8:11
  • Which version of truffle are you using?
    – wero026
    Jun 22, 2020 at 10:51

1 Answer 1


Turn out that Truffle v5 versions earlier than v5.1.5 won't successfully compile ^0.6.0 solidity contracts, because the solc wrapper Truffle used (directly from solc-js) was only compatible with ^0.5.0 contracts.

The solution is to update the truffle package using npm update -g truffle

Thanks to CruzMolina from GitHub !

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