I know there was a string limit but I thought that was long ago. I had a smart contract working but there is a limit of 32 bytes on the string input. I am unsure if a version changed or something like that. I had tested before and it was handling strings longer than 32 bytes. Now it does not.

When that is exceeded it does not insert any data. I ma using PoA now, I was testing with PoW before. But that should not make any difference.

I am running addInventory in the following contract.

Can someone clarify the allowed string length?

pragma solidity ^0.4.18;

// this contract stores the inventory strings, the hash of the string, and the keys to storage areas
// to add - events for updates, sha to check passed sha (if an error reject),

contract RegisterContract {

    uint public inventoryWeight;

    mapping(bytes32=>string) public inventories; // stores of json strings
    bytes32[] public inventoryHashes; // this is used mainly in testing eg inventoryHashes(uint) for the sequence of inventories added
    bytes32[] public inventoryHashesStorage; // keys to storage

    event eventNewInventory(bytes32 hashInventory);
    event eventNewStorageInventory(bytes32 hashInventory);

    function addInventory ( string inventory, bytes32 hashInventory) public {
        inventories[hashInventory] = inventory;

     function addInventoryHash(bytes32 hashInventory) public {
         // storage key - kept separate in case add addInventory fails due to gas limits
         // during testing addInventory did sometimes fail due to long strings
         // this hashInventory would be a key to IPFS or a database

    function getAllInventories() public view returns (bytes32[]) {
        return inventoryHashesStorage;

    function addWeight (uint weight) public {
        inventoryWeight = weight;

    function () payable public {

  • This works on Ropsten. So it is a geth issue. Jun 2, 2018 at 12:48

3 Answers 3


A variable of type bytes32 can't contain strings longer than 32 characters.

A variable of type string can contain a string of any size.

Do you have a reproduceable example where a string can't contain more than 32 characters? Maybe an etherscan link to a transaction on your contract?

  • I can send the connection details, if you have a PM here. Jun 2, 2018 at 11:59
  • > f1="jkhdfkjsdhfjdshkhskjghdfjkghkjdfhgjkdfhgkjfhgkjdfhgkjfhdgkjfhgkjfhgkjf" "jkhdfkjsdhfjdshkhskjghdfjkghkjdfhgjkdfhgkjfhgkjdfhgkjfhdgkjfhgkjfhgkjf" > eth.defaultAccount=eth.coinbase "0x0c12901e1ec7f80763cd433e8eca0c837d11a0c1" > con.addInventory(f1, web3.sha3(f1)) "0x8d506679b06d4d6cb4a81e0ab53f5a0abe7abfb12f7bb1cd04764c8bdc444eb9" > con.inventories(web3.sha3(f1)) "" > f1="hjkfhgfjghfjkg" "hjkfhgfjghfjkg" > con.addInventory(f1, web3.sha3(f1)) "0x737419aff198c110d3290e33bd5f0897c885983ebc57d41cd8b547f0df8c6858" > con.inventories(web3.sha3(f1)) "hjkfhgfjghfjkg" > Jun 2, 2018 at 12:16
  • 3
    I would like to clarify that, while in practice it is a string of any size, there is actually a limit of 2^256 * 256 bits or about 3.7 * 10^54 yottabytes. Jun 2, 2018 at 13:58
  • 2
    Technically it's (2^256 -1)*256 because of length encoding Jun 2, 2018 at 14:30
  • 2
    If you're going to consider that a limit, you should consider lots of other limitations (hard drive size, network speed, transaction fee, etc) which all cause even lower limits :)
    – Jesbus
    Jun 3, 2018 at 9:12

Maybe the hashes pushed into the array are longer than 32bytes. Btw, wouldn't it better to save the hashes in a mapping instead?

  • 1
    Hashes are all 32 bytes. There is a mapping already. Jun 2, 2018 at 12:34
  • web3.sha3(f1) is 66bytes "0x" included or 64bytes without "0x" prefix
    – user38075
    Jun 2, 2018 at 12:56
  • @siid That is the hexadecimal notation used in javascript, when encoded in a raw transaction it is just 32 bytes.
    – Ismael
    Jun 2, 2018 at 20:53

Gas cost - commodityContract.addInventory(mystrS, shastr, {gas: 4712000}); commodityContract.addInventoryHash(shastr,{gas: 4712000});

  • 2
    If this was intended to answer the question, please edit it to clarify how it answers the question that was asked.
    – eth
    Jun 3, 2018 at 17:16

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