I have been reading about Solidity release version 0.4.17. https://github.com/ethereum/solidity/releases

One of the following statements was really interesting:

We also worked further on the new ABI encoder: Functions can now return structs. Switch it on using pragma experimental ABIEncoderV2. It should already work, but still generates more expensive code.

I`ve been trying to simulate that in Remix but without any luck, I am getting this error:

"error": "Failed to decode output: Error: Unsupported or invalid type: tuple" Here is my code:

pragma solidity ^0.4.17;
pragma experimental ABIEncoderV2;
contract StructTest{
    struct someTestStruct {
        uint A;
        uint B;
        bytes32 C;
    someTestStruct str;
    function StructTest(){
        str = someTestStruct({A: 5, B: 6, C: "Hi"});
    // trying to get struct but getting "error": "Failed to decode output: Error: Unsupported or invalid type: tuple"
    function returnStruct() returns (someTestStruct){
        return str;

Have someone tried this? What am I doing wrong here? Thanks in advance!

3 Answers 3


Yes we can return structs.

But only in internal function calls.

pragma solidity ^0.4.19;

contract tester{

struct Person
    string name;
    uint age;

function getSome() public returns (Person a)
    Person memory p;
    p.name = "kashish";
    p.age =20;
    return p;

function wantSome() public returns (string,uint)
     Person memory p2 =getSome();
     return (p2.name,p2.age); // return multiple values like this

Might worth checking the Solidity compiler version in Remix's "Settings" menu. The code appears to be running OK in my test. So it could be the compiler isn't the latest.

  • 1
    Changing compiler version didn`t helped. Do you getting struct in "decoded output".?
    – Sivich
    Oct 30, 2017 at 8:51
  • Looks like my answer is wrong. I also got decode error when the details are expanded. It seems to not many ABIs support this yet. See github.com/ethereum/solidity/issues/2948 . So it seems at least it won't work with Remix (at least for now) Oct 30, 2017 at 23:32
  • Ok, thanks for your answer! I`ll try it with Truffle or Meteor then.
    – Sivich
    Oct 31, 2017 at 10:49

With the new solidity compiler this is possible. Probably you would have to end up adding the pragma declaration for experimental ABIEncoderV2 at the top of the contract definition file. I am using 0.5.9 and works fine.

pragma solidity ^0.5.9;
pragma experimental ABIEncoderV2;

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