Node JS Mysql PROTOCOL ENQUEUE AFTER FATAL ERROR

Question

What does the error mean?

{ [Error: Cannot enqueue Query after fatal error.] code: 'PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR', fatal: false }

This code works in my test file:

function handleDisconnect() {
    objConn = mysql.createConnection(db_config);    // Recreate the connection, since
                                                    // the old one cannot be reused.
    objConn.connect(function(err) {                 // The server is either down
        if(err) {                                   // or restarting (takes a while sometimes).
            console.log('error when connecting to db:', err.code);
            setTimeout(handleDisconnect, 2000);     // We introduce a delay before attempting to reconnect,
        }else{
            console.log('Connected to db!');
        }                                           // to avoid a hot loop, and to allow our node script to
    });                                             // process asynchronous requests in the meantime.
                                                    // If you're also serving http, display a 503 error.
    objConn.on('error', function(err) {
        if(err.code === 'PROTOCOL_CONNECTION_LOST') { // Connection to the MySQL server is usually
            handleDisconnect();                       // lost due to either server restart, or a
        }else{
            throw err;
        }
    });
}

handleDisconnect();
megaLoop();

function megaLoop(){
    objConn.query('SELECT u.`email` FROM `users` as u', function(err, rows) {
        console.log(err);
        console.log(rows);
    });
    setTimeout(megaLoop, 100); 
}

But when I use the function in my Express App I get the error:

{ [Error: Cannot enqueue Query after fatal error.] code: 'PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR', fatal: false }

Why does it work in my test and not my app?

Please visit answer to similar question http://stackoverflow.com/a/38418562/543087 — user5858, Jul 18 '16 at 07:03

score 12 · Answer 1 · answered Sep 06 '18 at 23:33

12

I had similar issue connecting with MySQL. I solved this issue using connection pool. The concept is to get a connection from a connection pool only when required and release it after use. That way the connection will not be in unstable state. You can get implementation details here.

answered Sep 06 '18 at 23:33

Sawal Maskey

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this is the correct answer.. many thanks, I had the same issue and fixed it by following this article – Jethik Oct 02 '18 at 11:49
Releasing connection every now and then doesn't sound like performance-wise solution. – jayarjo Nov 27 '18 at 16:28
1

@jayarjo I thought "release" in this context does not mean closing the connection. The connection remains active and is available in the pool to be used again. In fact, using a connection pool can improve performance by avoiding closing and reopening connections when you are running multiple requests asynchronously / in parallel. – JohnRC Sep 02 '20 at 11:44

score 2 · Answer 2 · edited Feb 24 '23 at 15:47

2

Open MySql Workbench or MySql Command line and type this:

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

Now, your password for root user is 'password', use that in your DB Connection, it's work

edited Feb 24 '23 at 15:47

Tyler2P

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answered Nov 14 '22 at 08:25

Nu'man Arif

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score 0 · Accepted Answer · edited May 23 '17 at 12:08

0

I believe the issue is an express-sql-session. I'm experiencing the same issue right now. I think someone is on to something at this post: NodeJS running on MAC, and have an error occurred when deploying on centOS

Check this out too: https://github.com/felixge/node-mysql/issues/1166

edited May 23 '17 at 12:08

Community

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answered Oct 14 '15 at 03:19

Scott

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Is this problem solved? I am getting exactly same issue. But I cannot find a solution in the answer here. – Sawal Maskey Sep 06 '18 at 14:07
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I'm not certain. I kind of gave up on mySQL (with node) and moved to mongoDB. I am still curious if the issue has be solved or not. – Scott Sep 06 '18 at 14:53
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Why is this the accepted answer? It doesn't answer and just gives out more links. – Filipe Madureira Dec 06 '19 at 09:10
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@Scott This is a terrible answer. It does not explain any solution, just more links. – Socrates Dec 27 '19 at 05:11
My issue was with the `.env` file. I was referring to the wrong password on the server. – Gimnath Oct 20 '21 at 16:40

score 0 · Answer 4 · answered Aug 08 '22 at 09:54

0

I had the same issue , only to find out my DB name on Nodejs was incorrectly named

answered Aug 08 '22 at 09:54

Vuyani Daweti

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score 0 · Answer 5 · edited Feb 24 '23 at 15:47

0

Open your MySQL command line client and run this command:

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'your_current_password';

Insert your password in <your_current_password>

edited Feb 24 '23 at 15:47

Tyler2P

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answered Sep 19 '22 at 06:34

Bilal Mohmand

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score 0 · Answer 6 · answered Nov 05 '22 at 15:58

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ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

1.use the above query in your mysql workbench replace 'password' with your actual password 2.then restart your server

answered Nov 05 '22 at 15:58

HimanshuGoyal

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score 0 · Answer 7 · edited Apr 15 '23 at 10:37

I am facing same problem, when I was working on my project, its problem with database connection file. So first of all check credential for database connectivity is given right. And then check password for accessing database from MySQL. Past following code to your workplace in mySQL which set database password null or empty.

'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '';

score 0 · Answer 8 · edited May 11 '23 at 20:45

0

I also faced this problem when I am trying to connect mysql as this is an authentication problem you can solve this problem just executing the below query in mysql workbench or any mysql command line.

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

edited May 11 '23 at 20:45

idchi

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answered May 08 '23 at 07:41

Ankit Kumar

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Node JS Mysql PROTOCOL ENQUEUE AFTER FATAL ERROR

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