Infura .watch Error: Invalid JSON RPC response: “”

Question

I’m trying to use the .watch() command on an event in my contract. Whenever I run the .js file, I’m presented with the following:

Error: Invalid JSON RPC response: “”

I’m not at my computer and can’t paste my .js file until later today, but what does this error suggest? It is displayed every time the file is executed. Could it be an issue with the contract instance or web3 itself?

Thank you in advance.

You are not able to connect to your node (I think you are using geth client). — Prashant Prabhakar Singh, May 15 '18 at 11:13
I am deploying the contract to the Ropsten test network via Remix and setting the web3 provider to the Ropsten Infura node — noob_23, May 15 '18 at 11:28
Infura doesn't support events using watch, you have to use subscribe from web3 v1.0 and the websocket endpoint. — Ismael, May 15 '18 at 19:39

score 1 · Accepted Answer · answered May 15 '18 at 23:26

1

As mentioned by Ismael, Infura doesn't support the use of .watch() events. The solution is to use the Infura websockets. Working code can be found here: Infura web3 provider for Events (.get & .watch)

answered May 15 '18 at 23:26

noob_23

11
3

score 0 · Answer 2 · answered May 15 '18 at 13:48

I also add issues using watch() on web3 to watch for events.

But I manage to solve them by using the alternative method (docs):

// Or pass a callback to start watching immediately
var event = myContractInstance.MyEvent([{valueA: 23}] [, additionalFilterObject] , function(error, result){
  if (!error)
    console.log(result);
});

For an event of this kind:

event singleNumber(uint256 number);

I get the value of it like this:

var event = myContractInstance.singleNumber({}, function(error, result){
  if (!error)
    var number = result.args.number.toNumber();
});

score 0 · Answer 3 · answered May 15 '18 at 14:00

0

There is github thread about this response: https://github.com/trufflesuite/truffle/issues/852

According to this it's an issue with Infura and open handlers.

answered May 15 '18 at 14:00

Arte

1

Infura .watch Error: Invalid JSON RPC response: “”

3 Answers3