I am having the following issue: When i send ETH to the contract i receive "Failed To Send" on the metamask wallet, and the warning on Remix is: Fallback function of contract requires too much gas (infinite). If the fallback function requires more than 2300 gas, the contract cannot receive Ether. I tried to find some tutorials to fix it but i did not was enable to find something useful and that i can understand. This is how the code i am using is: pragma solidity ^0.4.24; library SafeMath { /** * @dev Returns the addition of two unsigned integers, reverting on * overflow. * * Counterpart to Solidity 's `+` operator. * * Requirements: * - Addition cannot overflow. */ function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; require(c >= a, "SafeMath: addition overflow"); return c; } /** * @dev Returns the subtraction of two unsigned integers, reverting on * overflow (when the result is negative). * * Counterpart to Solidity' s `-` operator. * * Requirements: * - Subtraction cannot overflow. */ function sub (uint256 a, uint256 b) internal pure returns (uint256) { require (b <= a, "SafeMath: subtraction overflow" ); uint256 c = a - b; return c; } /** * @dev Returns the multiplication of two unsigned integers, reverting on * overflow. * * Counterpart to Solidity's `*` operator. * * Requirements: * - Multiplication cannot overflow. */ function mul (uint256 a, uint256 b) internal pure returns (uint256) { // Gas optimization: this is cheaper than requiring 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522 if (a == 0 ) { return 0 ; } uint256 c = a * b; require (c / a == b, "SafeMath: multiplication overflow" ); return c; } /** * @dev Returns the integer division of two unsigned integers. Reverts on * division by zero. The result is rounded towards zero. * * Counterpart to Solidity's `/` operator. Note: this function uses a * `revert` opcode (which leaves remaining gas untouched) while Solidity * uses an invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function div (uint256 a, uint256 b) internal pure returns (uint256) { // Solidity only automatically asserts when dividing by 0 require (b > 0 , "SafeMath: division by zero" ); uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), * Reverts when dividing by zero. * * Counterpart to Solidity's `%` operator. This function uses a `revert` * opcode (which leaves remaining gas untouched) while Solidity uses an * invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function mod (uint256 a, uint256 b) internal pure returns (uint256) { require (b != 0 , "SafeMath: modulo by zero" ); return a % b; } } contract Token { /* This is a slight change to the ERC20 base standard. function totalSupply() constant returns (uint256 supply); is replaced with: uint256 public totalSupply; This automatically creates a getter function for the totalSupply. This is moved to the base contract since public getter functions are not currently recognised as an implementation of the matching abstract function by the compiler. */ /// total amount of tokens uint256 public totalSupply; /// @param _owner The address from which the balance will be retrieved /// @return The balance function balanceOf (address _owner) public view returns (uint256 balance) ; /// @notice send `_value` token to `_to` from `msg.sender` /// @param _to The address of the recipient /// @param _value The amount of token to be transferred /// @return Whether the transfer was successful or not function transfer (address _to, uint256 _value) public returns (bool success) ; /// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from` /// @param _from The address of the sender /// @param _to The address of the recipient /// @param _value The amount of token to be transferred /// @return Whether the transfer was successful or not function transferFrom (address _from, address _to, uint256 _value) public returns (bool success) ; /// @notice `msg.sender` approves `_spender` to spend `_value` tokens /// @param _spender The address of the account able to transfer the tokens /// @param _value The amount of tokens to be approved for transfer /// @return Whether the approval was successful or not function approve (address _spender, uint256 _value) public returns (bool success) ; /// @param _owner The address of the account owning tokens /// @param _spender The address of the account able to transfer the tokens /// @return Amount of remaining tokens allowed to spent function allowance (address _owner, address _spender) public view returns (uint256 remaining) ; // solhint-disable-next-line no-simple-event-func-name event Transfer(address indexed _from, address indexed _to, uint256 _value); event Approval(address indexed _owner, address indexed _spender, uint256 _value); } contract StandardToken is Token { function transfer (address _to, uint256 _value) returns (bool success) { //Default assumes totalSupply can't be over max (2^256 - 1). //If your token leaves out totalSupply and can issue more tokens as time goes on, you need to check if it doesn't wrap. //Replace the if with this one instead. //if (balances[msg.sender] >= _value && balances[_to] + _value > balances[_to]) { if (balances[msg.sender] >= _value && _value > 0 ) { balances[msg.sender] -= _value; balances[_to] += _value; Transfer(msg.sender, _to, _value); return true ; } else { return false ; } } function transferFrom (address _from, address _to, uint256 _value) returns (bool success) { //same as above. Replace this line with the following if you want to protect against wrapping uints. //if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && balances[_to] + _value > balances[_to]) { if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0 ) { balances[_to] += _value; balances[_from] -= _value; allowed[_from][msg.sender] -= _value; Transfer(_from, _to, _value); return true ; } else { return false ; } } function balanceOf (address _owner) constant returns (uint256 balance) { return balances[_owner]; } function approve (address _spender, uint256 _value) returns (bool success) { allowed[msg.sender][_spender] = _value; Approval(msg.sender, _spender, _value); return true ; } function allowance (address _owner, address _spender) constant returns (uint256 remaining) { return allowed[_owner][_spender]; } mapping (address => uint256) balances; mapping (address => mapping (address => uint256)) allowed; uint256 public totalSupply; } contract MyToken is StandardToken { using SafeMath for uint256; uint256 constant private MAX_UINT256 = 2 ** 256 - 1 ; mapping (address => uint256) public balances; mapping (address => mapping (address => uint256)) public allowed; string public name; // Token Name uint8 public decimals; // How many decimals to show. To be standard complicant keep it 18 string public symbol; // An identifier: eg SBX, XPR etc.. string public version = 'H1.0' ; uint256 public unitsOneEthCanBuy; // How many units of your coin can be bought by 1 ETH? uint256 public totalEthInWei; // WEI is the smallest unit of ETH (the equivalent of cent in USD or satoshi in BTC). We'll store the total ETH raised via our ICO here. address public fundsWallet; // Where should the raised ETH go? // This is a constructor function // which means the following function name has to match the contract name declared above function MyToken () { balances[msg.sender] = 1000000000000000 ; // Give the creator all initial tokens. This is set to 1000 for example. If you want your initial tokens to be X and your decimal is 5, set this value to X * 100000. (CHANGE THIS) totalSupply = 1000000000000000 ; // Update total supply (1000 for example) (CHANGE THIS) name = "MyToken" ; // Set the name for display purposes (CHANGE THIS) decimals = 8 ; // Amount of decimals for display purposes (CHANGE THIS) symbol = "MYT" ; // Set the symbol for display purposes (CHANGE THIS) unitsOneEthCanBuy = 1000 ; // Set the price of your token for the ICO (CHANGE THIS) fundsWallet = msg.sender; // The owner of the contract gets ETH } function () payable { totalEthInWei = totalEthInWei + msg.value; uint256 amount = msg.value * unitsOneEthCanBuy; require (balances[fundsWallet] >= amount); balances[fundsWallet] = balances[fundsWallet] - amount; balances[msg.sender] = balances[msg.sender] + amount; Transfer(fundsWallet, msg.sender, amount); // Broadcast a message to the blockchain //Transfer ether to fundsWallet fundsWallet.transfer(msg.value); } /* Approves and then calls the receiving contract */ function approveAndCall (address _spender, uint256 _value, bytes _extraData) returns (bool success) { allowed[msg.sender][_spender] = _value; emit Approval(msg.sender, _spender, _value); require (!_spender.call(bytes4(bytes32(keccak256( "receiveApproval(address,uint256,address,bytes)" ))), msg.sender, _value, this, _extraData)); return true ; } function transfer (address _to, uint256 _value) public returns (bool success) { require (balances[msg.sender] >= _value); balances[msg.sender] -= _value; balances[_to] += _value; emit Transfer(msg.sender, _to, _value); //solhint-disable-line indent, no-unused-vars return true ; } function transferFrom (address _from, address _to, uint256 _value) public returns (bool success) { uint256 allowance = allowed[_from][msg.sender]; require (balances[_from] >= _value && allowance >= _value); balances[_to] += _value; balances[_from] -= _value; if (allowance < MAX_UINT256) { allowed[_from][msg.sender] -= _value; } emit Transfer(_from, _to, _value); //solhint-disable-line indent, no-unused-vars return true ; } function balanceOf (address _owner) public view returns (uint256 balance) { return balances[_owner]; } function approve (address _spender, uint256 _value) public returns (bool success) { allowed[msg.sender][_spender] = _value; emit Approval(msg.sender, _spender, _value); //solhint-disable-line indent, no-unused-vars return true ; } function allowance (address _owner, address _spender) public view returns (uint256 remaining) { return allowed[_owner][_spender]; } } Thank you for your attention,