When reinstalling the uninstalled MySQL service in Windows system, the reasons and solutions for failure to install occur

When reinstalling an uninstalled MySQL service on a Windows system, the installation may fail. The possible reasons are as follows:

1. The service is not completely uninstalled: Sometimes, the uninstallation process of MySQL may not be complete, causing the installation program to not correctly recognize the uninstalled status and thus unable to continue the installation. You can try to manually delete the uninstalled MySQL-related files and folders, including the installation directory and data folder.

2. Port occupied: MySQL uses port 3306 by default. If this port is already occupied by other programs, the installation of the MySQL service will fail.

3. Port conflicts: If the previous MySQL service was not shut down or uninstalled properly, it may cause a port conflict and prevent the new installation from successfully binding to the corresponding port.

4. Administrator rights issue: When reinstalling the MySQL service, you need to run the installation program with administrator rights, otherwise the necessary operations may not be completed.

Here are some solutions:

1. Clear residual files: Go to the folder where MySQL was previously installed and manually delete the remaining files and folders, including the installation directory and data files. You can also use system tools or third-party tools to clean up related entries in the registry to ensure that MySQL residual information is completely cleared.

2. Check and release the port: Open a command prompt window (run as administrator), enter the command  netstat -ano, and find if other applications are using the MySQL default port (usually 3306). If you find a conflicting port, close or modify the port settings of the corresponding application to free the port.

   netstat -ano | findstr :3306
    
   

3. Run the installer with administrator privileges: Make sure you run the MySQL installer with administrator privileges. Right-click the installer, select "Run as administrator" and follow the installation wizard to install.

4. Firewall or antivirus software interference: Check your firewall and antivirus software settings to make sure they are not blocking the MySQL installation process. You can try disabling them before installation and then re-enabling them after reinstallation is complete.

5. Other conflicting software: Sometimes, other installed software may conflict with the installation of MySQL, preventing it from installing properly. You can try temporarily uninstalling or disabling other software and then re-running the installer.

6. Using MySQL Installer: MySQL provides an official MySQL Installer tool, which can simplify the installation and configuration process. Try using it to install MySQL, it will handle many common installation issues and ensure that all dependencies and configurations are set up correctly.