Example.sol

pragma solidity ^0.6.0;

// Calling SafeERC20.safeTransfer and SafeERC20.safeTransferFrom can fail
// with a "SafeERC20: ERC20 operation did not succeed" message when the
// underlying cause is running out of gas inside the transfer

// This is because the low level call to the ERC20 is indeed reverted by
// running out of gas, but that revert is caught, and a different revert
// is raised by the safeTransfer method.


// Sample code for remix below.


pragma solidity ^0.6.0;

contract Caller{
    function doSafeTransfer(address other) public returns (bytes memory rd) {
        bytes memory data = abi.encodeWithSignature("transfer()");
        (bool success, bytes memory returndata) = address(other).call(data);
        require(success, "SafeERC20: ERC20 operation did not succeed");
        return returndata;
    }
}

contract Happy{
    function transfer() public {
        
    }
}

contract Sad {
    uint256 foo; 
    function transfer() public {
        for(uint256 i = 0; i < 400; i++){
            foo = i;
        }
    }
}