npm solc: AssertionError [ERR_ASSERTION]: Invalid callback specified

Question

I am trying to compile solidity smart contract using npm solc. I tried to follow different examples. Link to example: https://medium.com/coinmonks/how-to-compile-a-solidity-sma

Answer 1

I fixed the error with adding "npm install --save solc@0.4.25" in cmd. Error is the solidity version. you need to install old version of solidity to execute the compile script

Answer 2

If you are using latest version ie. 0.5.9 there is change in how you compile the code.

const path = require('path');
const fs = require('fs');
const solc = require('solc');



const helloPath = path.resolve(__dirname, 'contracts', 'hello.sol');
const source = fs.readFileSync(helloPath, 'UTF-8');

var input = {
    language: 'Solidity',
    sources: {
        'hello.sol' : {
            content: source
        }
    },
    settings: {
        outputSelection: {
            '*': {
                '*': [ '*' ]
            }
        }
    }
}; 
console.log(JSON.parse(solc.compile(JSON.stringify(input))));

Answer 3

This is because of version mismatch of solidity compiler installed during solc package installation and the compiler mentioned in the solidity file.To solve this issue try

install:

npm install solc@0.4.25

in solidity file use :

pragma solidity^0.4.25;

Answer 4

Check your code in Remix first, then check compiler version

Answer 5

• unistall solidity compiler

• using - npm uninstall solc

• then install required version of solidity compiler

• using - npm install solc@0.4.17

Answer 6

This is because the version mismatch of Solidity compiler. Please note or verify the solidity compiler version in which you want to work. For example: If you are doing work in

pragma solidity ^0.4.17

then you have to install 0.4.17 solidity compiler version like this:

npm install solc@0.4.17

in the command prompt or terminal.