Unable to connect to any of the specified mysql hosts. C# MySQL

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16
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I am getting the above error when I execute the code -

MySqlConnection mysqlConn=new MySqlConnection("server=127.0.0.1;uid=pankaj;port=3306;pwd=master;database=patholabs;");
        mysqlConn.Open();

I have tried setting server to localhost, user to root but I get the following error-

Error: 0 : Unable to connect to any of the specified MySQL hosts.
System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>DBSync.exe</AppDomain><Exception><ExceptionType>MySql.Data.MySqlClient.MySqlException, MySql.Data, Version=6.7.4.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d</ExceptionType><Message>Unable to connect to any of the specified MySQL hosts.</Message><StackTrace>
at  MySql.Data.MySqlClient.NativeDriver.Open()
at MySql.Data.MySqlClient.Driver.Open()
at MySql.Data.MySqlClient.Driver.Create(MySqlConnectionStringBuilder settings)
at MySql.Data.MySqlClient.MySqlPool.CreateNewPooledConnection()
at MySql.Data.MySqlClient.MySqlPool.GetPooledConnection()
at MySql.Data.MySqlClient.MySqlPool.TryToGetDriver()
at MySql.Data.MySqlClient.MySqlPool.GetConnection()
at MySql.Data.MySqlClient.MySqlConnection.Open()
at DBSync.MainForm.BtnCalculateClick(Object sender, EventArgs e) in c:\Documents  and Settings\Test01\My Documents\SharpDevelop Projects\DBSync\DBSync\MainForm.cs:line 51
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at DBSync.Program.Main(String[] args) in c:\Documents and Settings\Test01\My Documents\SharpDevelop Projects\DBSync\DBSync\Program.cs:line 27</StackTrace><ExceptionString>MySql.Data.MySqlClient.MySqlException (0x80004005): Unable to connect to any of the specified MySQL hosts.
at MySql.Data.MySqlClient.NativeDriver.Open()
at MySql.Data.MySqlClient.Driver.Open()
at MySql.Data.MySqlClient.Driver.Create(MySqlConnectionStringBuilder settings)
at MySql.Data.MySqlClient.MySqlPool.CreateNewPooledConnection()
at MySql.Data.MySqlClient.MySqlPool.GetPooledConnection()
at MySql.Data.MySqlClient.MySqlPool.TryToGetDriver()
at MySql.Data.MySqlClient.MySqlPool.GetConnection()
at MySql.Data.MySqlClient.MySqlConnection.Open()
at DBSync.MainForm.BtnCalculateClick(Object sender, EventArgs e) in c:\Documents and Settings\Test01\My Documents\SharpDevelop Projects\DBSync\DBSync\MainForm.cs:line 51
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at DBSync.Program.Main(String[] args) in c:\Documents and Settings\Test01\My Documents\SharpDevelop Projects\DBSync\DBSync\Program.cs:line 27</ExceptionString><DataItems><Data><Key>Server Error Code</Key><Value>1042</Value></Data></DataItems></Exception></TraceRecord>

I can connect to the mysql server through mysql workbench and query the database. It is only the code that doesn't work. Edit: I have noticed that the error crops up when I am using sharpdevelop and not when I am using Visual Studio.

c#
mysql
visual-studio-2010
sharpdevelop
asked on Stack Overflow Aug 1, 2013 by Opax Web • edited Dec 21, 2013 by Opax Web

15 Answers

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Sometimes spacing and Order of parameters in connection string matters (based on personal experience and a long night :S)

So stick to the standard format here

Server=myServerAddress; Port=1234; Database=myDataBase; Uid=myUsername; Pwd=myPassword;

answered on Stack Overflow Aug 1, 2013 by Tamim Al Manaseer
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Since this is the top result on Google:

If your connection works initially, but you begin seeing this error after many successful connections, it may be this issue.

In summary: if you open and close a connection, Windows reserves the TCP port for future use for some stupid reason. After doing this many times, it runs out of available ports.

The article gives a registry hack to fix the issue...

Here are my registry settings on XP/2003:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\MaxUserPort 0xFFFF (DWORD)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\MaxUserPort\TcpTimedWaitDelay 60 (DWORD)

You need to create them. By default they don't exists.

On Vista/2008 you can use netsh to change it to something like:

netsh int ipv4 set dynamicport tcp start=10000 num=50000

...but the real solution is to use connection pooling, so that "opening" a connection really reuses an existing connection. Most frameworks do this automatically, but in my case the application was handling connections manually for some reason.

answered on Stack Overflow Jun 13, 2015 by BlueRaja - Danny Pflughoeft • edited Jun 18, 2015 by BlueRaja - Danny Pflughoeft
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I am running mysql on a computer on a local network. MySQL Workbench could connect to that server, but not my c# code. I solved my issue by disconnecting from a vpn client that was running.

answered on Stack Overflow May 16, 2016 by Jimmy
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Update your connection string as shown below (without port variable as well):

MysqlConn.ConnectionString = "Server=127.0.0.1;Database=patholabs;Uid=pankaj;Pwd=master;"

Hope this helps...

answered on Stack Overflow Oct 26, 2015 by Murat Yıldız
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Sometime the problem could be on your windows firewall, make sure your server allow access to all port associated with your mysql database.

answered on Stack Overflow Aug 8, 2016 by Johnbosco Adam
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In my case the hosting had a whitelist for remote connection to MySql. Try to add your IP to whitelist in hosting admin panel.

answered on Stack Overflow Oct 8, 2019 by bozydarlelutko
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use SqlConnectionStringBuilder to simplify the connection 

System.Data.SqlClient.SqlConnectionStringBuilder builder = new System.Data.SqlClient.SqlConnectionStringBuilder();
builder["Initial Catalog"] = "Server";
builder["Data Source"] = "db";
builder["integrated Security"] = true;
string connexionString = builder.ConnectionString;
SqlConnection connexion = new SqlConnection(connexionString);
try { connexion.Open(); return true; }
catch { return false; }
answered on Stack Overflow Aug 1, 2013 by Lamloumi Afif
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Just ran into the same problem. Installing the .NET framework on the target machine solved the problem.

Better yet, make sure all required dependencies are present in the machine where the code will be running.

answered on Stack Overflow May 12, 2014 by Czar Pino • edited May 12, 2014 by Czar Pino
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for users running VS2013

In windows 10.

Check if apache service is running. since it gets replaced with World wide web service.

run netstat -n to check this.

stop the service. start apache. restart the service.

answered on Stack Overflow Aug 5, 2015 by gondwe • edited Aug 5, 2015 by Robert
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I was having the exact same error.

Here's what you need to do:

If you are using MAMP, close your server. Then click on the preferences button when you open up MAMP again (before restarting your server of course).

Then you will need to click on the ports tab, and click the button "Set Web and MySQL Ports to 80 & 3306".

answered on Stack Overflow Sep 27, 2017 by justinpees • edited Jan 11, 2018 by Zze
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Try this:

MySqlConnectionStringBuilder conn_string = new MySqlConnectionStringBuilder();
conn_string.Server = "127.0.0.1";
conn_string.Port = 3306;
conn_string.UserID = "root";
conn_string.Password = "myPassword";
conn_string.Database = "myDB";



MySqlConnection MyCon = new MySqlConnection(conn_string.ToString());

try
{
    MyCon.Open();
    MessageBox.Show("Open");
    MyCon.Close();
    MessageBox.Show("Close");
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}
answered on Stack Overflow Oct 3, 2017 by daniele3004
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If you are accessing the live database by using localhost URL then it will not work. Please deploy your service or website on IIS and create URL and then access the database by using new URL, It will work.

answered on Stack Overflow Jan 5, 2019 by chavanNil
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In my case by removing portion "port=3306;" from the connection string solved the problem.

answered on Stack Overflow Jul 3, 2019 by kohku
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I found the solution to my problem, I was having the same issue. Previously I had my connection string as this notice the port :3306 needs to be either attached to the server like that 127.0.0.1:3306 or removed from server like that Server=127.0.0.1;Port=3306 depending on your .NET environment:

"Server=127.0.0.1:3306;Uid=username;Pwd=password;Database=db;"

It was running fine until something happened which I am not sure exactly what it is, might be a recent update to my .NET application packages. It looks like format and spacing of the connection string is important. Anyways, the following format seems to be working for me:

"Server=127.0.0.1;Port=3306;Uid=username;Pwd=password;Database=db;"

Try either of the versions and see which one works for you.

Also I noticed that you are not using camel casing, this could be it. Make sure your property names are in capital casing like that

Server
Port
Uid
Pwd
Database
answered on Stack Overflow Sep 30, 2020 by Ahmad Khudeish
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using System;
using System.Linq;
using MySql.Data.MySqlClient;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            // add here your connection details
            String connectionString = "Server=localhost;Database=database;Uid=username;Pwd=password;";
            try
            {
                MySqlConnection connection = new MySqlConnection(connectionString);
                connection.Open();

                Console.WriteLine("MySQL version: " + connection.ServerVersion);
                connection.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }
            Console.ReadKey();
        }
    }
}

make sure your database server is running if its not running then its not able to make connection and bydefault mysql running on 3306 so don't need mention port if same in case of port number is different then we need to mention port

answered on Stack Overflow Nov 3, 2014 by Shafeek Ajmal • edited Aug 4, 2015 by HuBeZa

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