Troubleshooting Database Startup Failure

## Common Causes and Solutions

### 1. Port 13306 Is Already in Use

**Note**  
In versions earlier than V3.3.4.2, the occupied port may be `3306` instead of `13306`.

**Symptom**  
The MySQL service fails to start because the required port is already occupied by another process.

**Solution**

1. Check whether port `13306` is in use.

```bash
   # Linux
   sudo lsof -i :13306
   # or
   sudo netstat -tulnp | grep :13306
   ```

```bash
   # Windows
   netstat -ano | findstr :13306
   ```

2. Review the command output. A result similar to the following indicates that another process is listening on the port:

```bash
   tcp 0 0 0.0.0.0:13306 0.0.0.0:* LISTEN 1234
   ```

3. Stop the conflicting process by using its PID.

```bash
   # Linux
   sudo kill -9 <PID>
   ```

```bash
   # Windows
   taskkill /PID <PID> /F
   ```

4. Start the MySQL service again and confirm that it starts normally.

### 2. The LarkXR Installation Directory Was Changed

**Symptom**  
The database service fails to start after the LarkXR deployment directory has been moved or renamed.

**Cause**  
If LarkXR was previously installed and registered as a system service, changing the installation directory can leave the service with an outdated executable path.

**Solution**

1. Open Command Prompt as an administrator.
2. Delete the old `PxyMysql8` service registration:

```bash
   sc delete PxyMysql8
   ```

3. Restart the server to ensure the old service configuration is fully cleared.
4. After the server restarts, start the database service again and verify that it is running properly.