Deployment Failed | hit a require or revert statement somewhere in its constructor

Question

I create a custom ERC20Token and a contract to store data sent from web3.Js. after storing data in mapping I would like to call ERC20Token contracts functionality inside this contract.

code of contract to store data in mapping.

import './EMPToken.sol';
contract socialposts {

//address payable public  owner;
EMPToken token;
address _empTokenAdr = 0xd3591733C103EaCfBE7e0c2b4C037764dA836FDe;
constructor() public {
// owner = msg.sender;

createPost('I am using Blokchain','David Abrahim');

}
function createPost(string memory content,string memory name) public {
   postCount++;
   posts[postCount] = post(postCount,content,name,msg.sender);
   //msg.sender.transfer(msg.value);
   token = EMPToken(_empTokenAdr);
   token.approve(msg.sender,2);
   }
}

Below are the version information Truffle v5.1.5 (core: 5.1.5) Solidity v0.5.12 (solc-js) Node v10.16.3 Web3.js v1.2.1

I am using Ganache blockchain with truffle. "socialposts" is a contract that takes input from UI and stores(I didnt include all code of this contract here). EMPToken.sol is my custom ERC Token. I want to trigger the "transfer" function of ERCToken inside "socialposts" contract.

Below is the error message i am getting

Error: * Deployment Failed *

"socialposts" hit a require or revert statement somewhere in its constructor. Try: * Verifying that your constructor params satisfy all require conditions. * Adding reason strings to your require statements.

Answer 1

I found this solution working. I didnt change any line of code apart from the below

Previous

token = EMPToken(_empTokenAdr);
token.approve(msg.sender,2);

Changed:

EMPToken(_empTokenAdr).approve(msg.sender,2);

I have no clue about the reasons.