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How to Fix “brew services start MySQL” Error

The “brew services start MySQL” command in macOS starts the MySQL service using Homebrew’s service management tool.

However, errors can sometimes prevent MySQL from starting properly. Today, we will look at some commonly seen errors and how to resolve theM.

Common Errors When Starting MySQL with Homebrew

1. Port Conflict (Port 3306 is Already in Use)

   In this case, MySQL fails to start. We also get the following error message:

   ERROR! The server quit without updating PID file.

   Click here for the Solution.

   1. Identify if another process is using MySQL’s default port (3306):

      sudo lsof -i :3306
   2. If another process is listed, stop it:

      sudo kill -9 PID

      Replace PID with the process ID.
   3. Restart MySQL:

      brew services start mysql

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2. Permission Issues

   Here, MySQL refuses to start or throws “permission denied” errors. Furthermore, logs will show errors like `InnoDB: Unable to lock ./ibdata1` or `Can’t create/write to file`.

   Click here for the Solution.

   1. Verify ownership of MySQL’s data directory:

      ls -ld /usr/local/var/mysql
   2. Update ownership if necessary:

      sudo chown -R $(whoami) /usr/local/var/mysql
   3. Set correct permissions:

      sudo chmod -R 755 /usr/local/var/mysql
   4. Restart MySQL:

      brew services restart mysql
3. Corrupted MySQL Files

   Errors related to InnoDB or tablespace file corruption.

   Click here for the Solution.

   1. Move the existing data directory to create a backup:

      mv /usr/local/var/mysql /usr/local/var/mysql_backup
   2. Reinitialize MySQL:

      mysqld –initialize
   3. Restart MySQL:

      brew services start mysql
4. MySQL Not Installed or Misconfigured

   In this case, Homebrew reports MySQL is not installed. Error messages indicate missing binaries or configuration files.

   Click here for the Solution.

   1. Reinstall MySQL via Homebrew:

      brew reinstall mysql
   2. Link MySQL correctly:

      brew link mysql
   3. Start MySQL:

      brew services start mysql
5. Configuration File Errors (my.cnf)

   In this case, MySQL fails to start due to invalid configurations in `my.cnf`. Also, logs contain syntax or configuration error messages.

   Click here for the Solution.

   1. Verify and correct the `my.cnf` file (default location: `/usr/local/etc/my.cnf`).
   2. If unsure, back up the file and use default settings:

      mv /usr/local/etc/my.cnf /usr/local/etc/my.cnf_backup
   3. Restart MySQL:

      brew services restart mysql
6. Log and PID File Problems

   In this case, we will see an error message as seen below:

   MySQL quit without updating PID file.

   Also, logs mention issues with `mysql.pid` or `error.log.`

   Click here for the Solution.

   1. Remove existing PID files:

      rm /usr/local/var/mysql/*.pid
   2. Restart MySQL:

      brew services restart mysql

Debugging with Logs

When we run into errors, the first step to debugging is to check MySQL’s logs for detailed error messages.
MySQL’s logs are usually located in /usr/local/var/mysql/.

General Troubleshooting Steps

1. Stop MySQL if partially running:

   brew services stop mysql
2. Ensure no other MySQL instances are running:

   ps aux | grep mysql
3. Restart MySQL:

   brew services restart mysql
4. Run Homebrew’s doctor command to identify potential issues:

   brew doctor
5. Check for service misconfigurations:

   brew services list

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Conclusion

By following these steps, we can identify and resolve the common issues that prevent MySQL from starting on macOS when using Homebrew.

In brief, our Support Experts demonstrated how to handle “brew services start MySQL” errors.