Solidity : Getting error as Member “balance” not found or not visible after argument-dependent lookup

Question

I am trying to write a Decentralization App to buy a concert ticket. For some reason, the part owner.transfer(this.balance) keeps giving me error. Also since solidity has too many version, I can't find a the best for mine. please help me in this. Thank you

Erro Message

Getting error as Member “balance” not found or not visible after argument-dependent lookup. Use address(this).balance to access address owner.transfer(this.balance)

Solidity Code

pragma solidity 0.6.6;

contract Event {
    
    address owner;
    uint public tickets;
    string public description;
    string public website;
    uint constant price = 0.01 ether;
    mapping (address => uint) public purchasers;
    
    constructor(uint t,  string memory _description, string memory _webstite) public {
        owner = msg.sender;
        description = _description;
        website = _webstite;
        tickets = t;
    }
    
    // function () payable {
    //     buyTickets(1);
    // }
    
    function buyTickets(uint amount) public payable {
        if (msg.value != (amount * price) || amount > tickets) {
            revert();
        }
        purchasers[msg.sender] += amount;
        tickets -= amount;
        if (tickets == 0) {
            owner.transfer(this.balance);
        }
    }
    
    function refund(uint numTickets)  public {
        if (purchasers[msg.sender] < numTickets) {
            revert();
        }
        
        msg.sender.transfer(numTickets * price);
        purchasers[msg.sender] -= numTickets;
        tickets += numTickets;
    }
    
}

After I change it to owner.transfer(address(this).balance);, it gave me another error.

[vm] from: 0x5b3...eddc4to: Event.buyTickets(uint256) 0xd91...39138value: 0 weidata: 0x2f3...00001logs: 0hash: 0x030...bbdf1
status  0x0 Transaction mined but execution failed
 transaction hash   0x03045aab3f5d40ebeef4eacedf50ce506edfc2b75c279652839fd74f8e9bbdf1 
 from   0x5b38da6a701c568545dcfcb03fcb875f56beddc4 
 to Event.buyTickets(uint256) 0xd9145cce52d386f254917e481eb44e9943f39138 
 gas    3000000 gas 
 transaction cost   21760 gas 
 execution cost 296 gas 
 hash   0x03045aab3f5d40ebeef4eacedf50ce506edfc2b75c279652839fd74f8e9bbdf1 
 input  0x2f3...00001 
 decoded input  { "uint256 amount": { "_hex": "0x01" } } 
 decoded output {} 
 logs   []  
 value  0 wei 
transact to Event.buyTickets errored: VM error: revert. revert The transaction has been reverted to the initial state. Note: The called function should be payable if you send value and the value you send should be less than your current balance. Debug the transaction to get more information.

Answer 1

transfer is only able for payable address. try as follows.

address payable owner;
...
owner.transfer(address(this).balance);