I’m a beginner in the Ethereum world and I’ve got some problems dealing with a SimpleStorage contract on my private testnet (http://solidity.readthedocs.io/en/latest/introduction-to-smart-contracts.html). In particular, if I create a contract instance and then call the set() function from the same node everything works. But if I call the set() function from another node of my private testnet by using the following commands:

> var instance = web3.eth.contract(abi).at(contractAddress);
> instance.set.sendTransaction(21, {from: web3.eth.accounts[0]});

the function does not seem to work. More precisely, by simply adding some event listeners, I can notice that the fallback function gets called instead. Could anyone tell me why? What am I doing wrong?

Any help appreciated.

  • Are you sure the ABI's correct? You'd see this behaviour if you're trying to call a function that doesn't exist, or has different formal parameters to the one you implemented. May 18, 2016 at 15:53
  • That was actually the problem. Now it works perfectly. Thanks a lot!
    – AM122
    May 18, 2016 at 16:29
  • 1
    @AM122 Way to go adding an event listener. Since no one else knows what the mistake was in the ABI, you probably want to post the answer to your own question, then in a few days you can accept the answer. Posting own answer is fine here.
    – eth
    May 18, 2016 at 19:38
  • There was a mistake in the abi definition of the input type (it was simply defined as 'uint' instead of 'uint256'). Thanks again
    – AM122
    May 20, 2016 at 8:58
  • @AM122 I meant to post in the big "your answer" box below, instead of this small box which is only for comments. Then in a couple of days, you can click checkmark on your answer.
    – eth
    May 23, 2016 at 12:48

1 Answer 1


There was a mistake in the abi definition of the input type (it was simply defined as 'uint' instead of 'uint256').

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