Cannot enqueue Handshake after invoking quit

Question

I have implemented the following code  module exports         getDataFromUserGps  function callback                connection connect            connection query  quot SELECT   FROM usergps quot                function err  results  fields                    if  err  return callback err  null                   return callback null  results                                     connection end               loginUser  function login  pass  callback                connection connect            connection query               quot SELECT id FROM users WHERE login     AND pass     quot                login  pass               function err  results  fields                                 if  err  return callback err  null                   return callback null  results                                     connection end               getUserDetails  function userid  callback                connection connect            connection query               quot SELECT   FROM userProfilDetails LEFT JOIN tags ON userProfilDetails userId   tags userId WHERE userProfilDetails userid     quot                userid               function err  results  fields                                if  err  return callback err  null                   return callback null  results                                    connection end               addTags  function userId  tags                connection connect            connection query               quot INSERT INTO tag  userId  tag  VALUES        quot                userId  tags               function err  results  fields                                if  err  throw err                                  connection end             Everything works great only for the first time  If I want to  quot use quot  the query for the second time I get the following error  Cannot enqueue Handshake after invoking quit  I have tried not to  end   connections but it didn t help  How can I fix this issue

User · Answer

If you re trying to get a lambda  I found that ending the handler with context done   got the lambda to finish  Before adding that 1 line  It would just run and run until it timed out

User · Answer

I think this issue is similar to mine    Connect to MySQL End MySQL service  should not quit node script  Start MySQL service  Node reconnects to MySQL Query the DB -  FAIL  Cannot enqueue Query after fatal error     I solved this issue by recreating a new connection with the use of promises  q    mysql-con js   use strict   var config            require       config js    var colors            require  colors    var mysql             require  mysql    var q                 require  q    var MySQLConnection        MySQLConnection connect   function        var d   q defer        MySQLConnection connection   mysql createConnection           host                   localhost           user                   root           password               password           database               database               MySQLConnection connection connect function  err            if err                console log  Not connected   red  err toString   red    RETRYING     blue               d reject              else               console log  Connected to Mysql  Exporting    blue               d resolve MySQLConnection connection                         return d promise      module exports   MySQLConnection    mysqlAPI js  var colors            require  colors    var mysqlCon          require    mysql-con js    mysqlCon connect   then function con      console log  connected         mysql   con      mysql on  error   function  err  result            console log  error occurred  Reconneting     purple           mysqlAPI reconnect                mysql query  SELECT 1   1 AS solution   function  err  results                if err  console log  err  err               console log  Works bro   results                mysqlAPI reconnect   function        mysqlCon connect   then function con         console log  connected  getting new reference            mysql   con          mysql on  error   function  err  result                mysqlAPI reconnect                       function  error          console log  try again            setTimeout mysqlAPI reconnect  2000                I hope this helps

User · Answer

According to    Fixing Node Mysql  Error  Cannot enqueue Handshake after invoking quit     http   codetheory in fixing-node-mysql-error-cannot-enqueue-handshake-after-invoking-quit       TL DR You need to establish a new connection by calling the createConnection method after every disconnection    and     Note  If you re serving web requests  then you shouldn t be ending connections on every request  Just create a connection on server   startup and use the connection client object to query all the time    You can listen on the error event to handle server disconnection and   for reconnecting purposes  Full code   here      From    Readme md - Server disconnects   https   github com felixge node-mysql server-disconnects   It says      Server disconnects      You may lose the connection to a MySQL server due to network problems    the server timing you out  or the server crashing  All of these events   are considered fatal errors  and will have the err code      PROTOCOL CONNECTION LOST    See the Error   Handling section for more information       The best way to handle such unexpected disconnects is shown below   function handleDisconnect connection      connection on  error   function err        if   err fatal          return             if  err code      PROTOCOL CONNECTION LOST           throw err             console log  Re-connecting lost connection      err stack        connection   mysql createConnection connection config       handleDisconnect connection       connection connect             handleDisconnect connection         As you can see in the example above  re-connecting a connection is   done by establishing a new connection  Once terminated  an existing   connection object cannot be re-connected by design       With Pool  disconnected connections will be removed from the pool   freeing up space for a new connection to be created on the next   getConnection call      I have tweaked the function such that every time a connection is needed  an initializer function adds the handlers automatically   function initializeConnection config        function addDisconnectHandler connection            connection on  error   function  error                if  error instanceof Error                    if  error code      PROTOCOL CONNECTION LOST                         console error error stack                       console log  Lost connection  Reconnecting                            initializeConnection connection config                     else if  error fatal                        throw error                                                         var connection   mysql createConnection config           Add handlers      addDisconnectHandler connection        connection connect        return connection      Initializing a connection   var connection   initializeConnection       host   localhost       user   user       password   password        Minor suggestion  This may not apply to everyone but I did run into a minor issue relating to scope  If the OP feels this edit was unnecessary then he she can choose to remove it  For me  I had to change a line in initializeConnection  which was var connection   mysql createConnection config   to simply just  connection   mysql createConnection config     The reason being that if connection is a global variable in your program  then the issue before was that you were making a new connection variable when handling an error signal  But in my nodejs code  I kept using the same global connection variable to run queries on  so the new connection would be lost in the local scope of the initalizeConnection method  But in the modification  it ensures that the global connection variable is reset This may be relevant if you re experiencing an issue known as     Cannot enqueue Query after fatal error   after trying to perform a query after losing connection and then successfully reconnecting  This may have been a typo by the OP  but I just wanted to clarify

User · Answer

Do not connect   and end   inside the function  This will cause problems on repeated calls to the function  Make the connection only  var connection   mysql createConnection         host   localhost         user   node         password   node         database   node project          connection connect function err        if  err  throw err        once and reuse that connection   Inside the function   function insertData name id       connection query  INSERT INTO members  name  id  VALUES           name id   function err result          if err  throw err

User · Answer

I had the same problem and Google led me here  I agree with  Ata that it s not right to just remove end    After further Googling  I think using pooling is a better way   node-mysql doc about pooling  It s like this   var mysql   require  mysql    var pool    mysql createPool        pool getConnection function err  connection        connection query   bla bla   function err  rows            connection release

User · Answer

inplace of connection connect    use -  if  connection  connectCalled      connection connect        if it is already called then connection  connectCalled  true   amp  it will not execute connection connect     note - don t use connection end

User · Answer

AWS Lambda functions     Use mysql createPool   with connection destroy     This way  new invocations use the established pool  but don t keep the function running  Even though you don t get the full benefit of pooling  each new connection uses a new connection instead of an existing one   it makes it so that a second invocation can establish a new connection without the previous one having to be closed first   Regarding connection end    This can cause a subsequent invocation to throw an error  The invocation will still retry later and work  but with a delay   Regarding mysql createPool   with connection release    The Lambda function will keep running until the scheduled timeout  as there is still an open connection   Code example  const mysql   require  mysql     const pool   mysql createPool     connectionLimit  100    host      process env DATABASE HOST    user      process env DATABASE USER    password  process env DATABASE PASSWORD       exports handler    event    gt      pool getConnection  error  connection    gt        if  error  throw error      connection query         INSERT INTO table name  event  VALUES     event           function error  results  fields          if  error  throw error        connection destroy

User · Answer

SOLUTION  to prevent this error for AWS LAMBDA    In order to exit of  Nodejs event Loop  you must end the connection  and then reconnect  Add the next code to invoke the callback   connection end  function err            if  err   console log  Error ending the connection   err                reconnect in order to prevent the Cannot enqueue Handshake after invoking quit            connection   mysql createConnection                   host        rds host                   port        3306                  user        user                  password    password                  database    target database                              callback null                statusCode  200              body  response

User · Answer

You can use  debug  false   Example    mysql connection  var dbcon1   mysql createConnection         host   localhost         user   root         password            database   node5         debug  false

User · Answer

If you using the node-mysql module  just remove the  connect and  end   Just solved the problem myself   Apparently they pushed in unnecessary code in their last iteration that is also bugged   You don t need to connect if you have already ran the createConnection call

[node.js] Cannot enqueue Handshake after invoking quit

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