Starting MySQL. ERROR! The server quit without updating PID file (/usr/local/mysql-8.0/data//localhost.localdomain.pid).

This error typically occurs when there is an issue with starting the MySQL server. Here are a few steps you can try to troubleshoot the problem: 1. Check the error log: Open the MySQL error log file, which is usually located at `/var/log/mysql/error.log` or `/usr/local/mysql/data/hostname.err`. Look for any error messages or warnings that might provide more information about the issue. 2. Verify file permissions: Ensure that the MySQL data directory and its files are owned by the MySQL user and group. You can use the following command to check and fix the permissions: ``` chown -R mysql:mysql /var/lib/mysql ``` 3. Remove the PID file: If the PID file mentioned in the error message exists, try removing it and restarting MySQL. Use the following command to remove the file: ``` sudo rm /usr/local/mysql-8.0/data//localhost.localdomain.pid ``` 4. Check disk space: Make sure that there is sufficient disk space available on your server. Use the following command to check disk usage: ``` df -h ``` 5. Check for conflicting processes: There might be another instance of MySQL already running or some other process using the same port (usually 3306). Use the following command to check for any running MySQL processes: ``` ps aux | grep mysql ``` If none of these steps resolve the issue, please provide more details about your environment, MySQL version, and any recent changes you made that might have caused this problem.