Issue with websocket connection to Moralis Server

Technical Issue Reporting
#1

Hi there,

Since speedy nodes are deprecated, I’m currently using LiveQuery to listen to new events (performed smart contract event syncs before). However, sometimes I’m facing this issue when starting:

Error: Unexpected server response: 503
    at ClientRequest.<anonymous> (/root/project/node_modules/ws/lib/websocket.js:604:7)
    at ClientRequest.emit (events.js:314:20)
    at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:601:27)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:122:17)
    at TLSSocket.socketOnData (_http_client.js:474:22)
    at TLSSocket.emit (events.js:314:20)
    at addChunk (_stream_readable.js:297:12)
    at readableAddChunk (_stream_readable.js:272:9)
    at TLSSocket.Readable.push (_stream_readable.js:213:10)
    at TLSWrap.onStreamRead (internal/stream_base_commons.js:188:23)
Emitted 'error' event on WebSocket instance at:
    at abortHandshake (/root/project/node_modules/ws/lib/websocket.js:731:15)
    at ClientRequest.<anonymous> (/root/project/node_modules/ws/lib/websocket.js:604:7)
    [... lines matching original stack trace ...]
    at TLSSocket.Readable.push (_stream_readable.js:213:10)
(node:11285) UnhandledPromiseRejectionWarning: Error: Received an error with invalid JSON from Parse: <html>
<head><title>502 Bad Gateway</title></head>
<body>
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx/1.18.0 (Ubuntu)</center>
</body>
</html>

Can you please tell me how to fix? Thank you
FYI, I use Moralis Node with serverUrl, appId and masterKey opts.

#2

Hi, I don’t know what is the code that you tried, you should be able to use a live query, or to connect directly to mongo db too if you want.

We are working now on an API specific for event syncs that could help you.

#3

Hi,

Actually, LiveQuery works fine when I run the script on my local computer. However, I don’t have any idea why sometimes I open the script on another server, it got the mentioned error.

This is a bunch of my code:

const Moralis = require('moralis/node');
const moralisConfig = require('./.moralis.json');

const startConnection() = async () => {
    await Moralis.start(moralisConfig);
    const query = new Moralis.Query("Transfer");
    const subscription = await query.subscribe();
    subscription.on('update', async (object) => {
        console.log(object);
    });
};

startConnection();

Currently, I could hotfix it by listening to error event and retry to connect to the server, but I am still looking for a better solution.

BTW, can’t wait to see your event syncs API. Good work guys.

#4

Maybe you could subscribe to more events to see if you get more information about what happens. But it looks like you get another type of error.