How to Change MySQL Port on Windows: Step-by-Step Configuration Guide


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When attempting to change MySQL's default port (3306) on Windows, many developers encounter the challenge of missing configuration files. MySQL searches for configuration in this order:


    

  • %WINDIR%\my.ini
    • 

  • %WINDIR%\my.cnf
    • 

  • C:\my.ini
    • 

  • C:\my.cnf
    • 

  • INSTALLDIR\my.ini
    • 

  • INSTALLDIR\my.cnf
    • 





When no configuration files exist (common with newer MySQL installations), you'll need to create one. Here's the proper way to create a working configuration:



# Example my.ini configuration
[client]
port=44999

[mysqld]
port=44999
# Important: Add your existing configuration here
basedir="C:/Program Files/MySQL/MySQL Server 5.5/"
datadir="C:/ProgramData/MySQL/MySQL Server 5.5/Data"



After creating/modifying the my.ini file, you must properly restart the MySQL service:


# Command line method (admin privileges required)
net stop MySQL55
net start MySQL55

# Alternative using PowerShell
Restart-Service -Name MySQL55 -Force



To confirm MySQL is listening on the new port:


# Using command line
netstat -ano | findstr 44999

# MySQL client verification
mysql --port=44999 -u root -p



If the service fails to start after port change:


    

  1. Check Windows Event Viewer for MySQL errors
    2. 

  2. Verify file permissions on my.ini (Administrators: Full Control)
    3. 

  3. Ensure no other services are using the new port
    4. 

  4. Add explicit bind-address if needed:
    5. 



[mysqld]
port=44999
bind-address=127.0.0.1



For persistent configuration, modify the service definition:


# First find the current service binary path
sc qc MySQL55

# Then update with new configuration file path
sc config MySQL55 binPath= "\"C:\Program Files\MySQL\MySQL Server 5.5\bin\mysqld\" --defaults-file=\"C:\Program Files\MySQL\MySQL Server 5.5\my.ini\" MySQL55"







Many Windows users struggle to find where MySQL actually reads its configuration. Unlike Linux systems where files are typically in /etc/my.cnf, Windows installations can be more ambiguous. MySQL searches these locations in order:


1. %WINDIR%\my.ini
2. %WINDIR%\my.cnf 
3. C:\my.ini
4. C:\my.cnf
5. INSTALLDIR\my.ini
6. INSTALLDIR\my.cnf



For MySQL 5.5+ installations, the most reliable location is typically:


C:\ProgramData\MySQL\MySQL Server 5.5\my.ini


The minimal configuration needed to change ports requires these sections:


[client]
port=44999

[mysqld]
port=44999



For a production server, you should also specify:


[mysqld]
port=44999
bind-address=0.0.0.0
max_connections=200



After modifying the configuration:


    

  1. Stop MySQL service: net stop MySQL55
    2. 

  2. Verify no mysqld process remains in Task Manager
    3. 

  3. Start MySQL service: net start MySQL55
    4. 



Check active ports using PowerShell:


Get-NetTCPConnection -LocalPort 44999



Or test connection from MySQL client:


mysql --port=44999 -u root -p



Create a new firewall rule for the custom port:


New-NetFirewallRule -DisplayName "MySQL Custom Port" -Direction Inbound -LocalPort 44999 -Protocol TCP -Action Allow



If MySQL reverts to 3306:


    

  • Check for duplicate my.ini files
    • 

  • Verify file permissions (Administrators: Full Control)
    • 

  • Inspect error logs: C:\ProgramData\MySQL\MySQL Server 5.5\Data\*.err
    •