The code is in src/socket.io/posts.js, but I can't find the topic_id and app.currentRoom you mention.

I got this error in browser client, don't know what it will take affect and how to solve?

WebSocket connection to 'ws://<myhost>/socket.io/?EIO=3&transport=websocket&sid=wW5Z4UKR9a_ZHKHkAAAF' failed: Error during WebSocket handshake: Unexpected response code: 400

which port it's using, I just open the port 4567 in firewall.

temp solution:

-- 	if(!data || !data.pid || !data.room_id) {
++ if(!data || !data.pid) {

the debug output as below:

4/6 03:55 [387] - info: command=`"upvote"
4/6 03:55 [387] - info: eventName=`"voted"
4/6 03:55 [387] - info: notification=`"notifications:upvoted_your_post_in"
4/6 03:55 [387] - info: data=`{"pid":"85","room_id":""}
4/6 03:55 [387] - error: favouriteCommand invalid-data

Does anyone have idea what's going wrong?

I found the error is come from favouriteCommand, and added some debug output:

    function favouriteCommand(socket, command, eventName, notification, data, callback) {
    winston.info('command=`' + JSON.stringify(command) );
    winston.info('eventName=`' + JSON.stringify(eventName) );
    winston.info('notification=`' + JSON.stringify(notification) );
    winston.info('data=`' + JSON.stringify(data) );

        if(!data || !data.pid || !data.room_id) {
    winston.error('favouriteCommand invalid-data');
            return callback(new Error('[[error:invalid-data]]'));
        }

I had changed to nodebb-theme-persona, it has the same problem.

1. CentOS release 6.6 (Final)

2. #git rev-parse HEAD
   d9af2242a7c7fc92318a83bd46e4f849094960f2

3. I am not using nodebb-theme-persona, but nodebb-theme-lavender.

4. error at client-side
   "Error
   Invalid Data"

@Mega Thanks Mega!
I know this can work, I expect the formal release for this.

nodebb-plugin-emailer-local can not get config value from plugin settings.
I just hard code and make it works.
BTW, secureConnection setting is useful, when using default sendmail service in Linux.

var transportOptions = {
secureConnection: false,
//        host: Meta.config['emailer:local:host'],
//        port: Meta.config['emailer:local:port']
    host: "10.175.191.88",
    port: 25
};

I want to vote a post in my nodebb, but nothing happen, no error log.
how can I debug?

problem solved with the latest fix, thanks~

code changes to avoid the crash, but peoples with dirty data can not see chat message from each other.

			function(messages, next) {
				async.map(messages, function(message, next) {
			if(typeof message === 'undefined') {                               //changes
				winston.error('message is undefined.');
			}else {
				winston.info('message=`' + JSON.stringify(message) );

					var self = parseInt(message.fromuid, 10) === parseInt(fromuid, 10);
					message.fromUser = self ? userData[0] : userData[1];
					message.toUser = self ? userData[1] : userData[0];
					message.timestampISO = utils.toISOString(message.timestamp);
					message.self = self ? 1 : 0;
					message.newSet = false;

					Messaging.parse(message.content, message.fromuid, fromuid, userData[1], userData[0], isNew, function(result) {
						message.content = result;
						next(null, message);
					});
			}

this error due to the dirty data in database,
I am using mongodb, but not clear how to clean up the chat message

As my analysis, email.json is no problem, it's the bug in the plugin

but the fact is it throw exception and nodebb crashed.

meta.config contains settings from NodeBB itself. Plugins retrieve their own settings via the settings module on the client side.
pls reference:
https://community.nodebb.org/topic/4449/can-t-find-constants-in-meta-config

source code should be fixed

                    try {
                            callback(JSON.parse(data.toString()));
                    } catch (e) {
                            winston.error('Could not parse `' + filename + '.json`, syntax error? Skipping...');
                            callback({});    // this callback is unnecessary 
                    }

error log:
20/5 08:00 [179] - error: Could not parse email.json, syntax error? Skipping...
20/5 08:00 [179] - error: Error: Callback was already called.
at /opt/nodebb/node_modules/async/lib/async.js:30:31
at /opt/nodebb/node_modules/async/lib/async.js:251:21
at /opt/nodebb/src/emailer.js:45:6
at /opt/nodebb/public/src/modules/translator.js:160:6
at /opt/nodebb/public/src/modules/translator.js:180:4
at /opt/nodebb/public/src/modules/translator.js:226:6
at /opt/nodebb/public/src/modules/translator.js:289:5

nodebb crash when read chat message, error log as below:
20/5 02:48 [246] - error: TypeError: Cannot read property 'fromuid' of undefined
at /opt/nodebb/src/messaging.js:146:34
at /opt/nodebb/node_modules/async/lib/async.js:249:17
at /opt/nodebb/node_modules/async/lib/async.js:125:13

nothing I can get from the log, I wonder if it's fired.
that's why I need to debug it.