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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 :3306Copy Code
   2. If another process is listed, stop it:

       sudo kill -9 PIDCopy Code

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

      brew services start mysqlCopy Code

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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/mysqlCopy Code
   2. Update ownership if necessary:

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

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

      brew services restart mysqlCopy Code
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_backupCopy Code
   2. Reinitialize MySQL:

      mysqld –initializeCopy Code
   3. Restart MySQL:

      brew services start mysqlCopy Code
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 mysqlCopy Code
   2. Link MySQL correctly:

      brew link mysqlCopy Code
   3. Start MySQL:

      brew services start mysqlCopy Code
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_backupCopy Code
   3. Restart MySQL:

      brew services restart mysqlCopy Code
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/*.pidCopy Code
   2. Restart MySQL:

      brew services restart mysqlCopy Code

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 mysqlCopy Code
2. Ensure no other MySQL instances are running:

   ps aux | grep mysqlCopy Code
3. Restart MySQL:

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

   brew doctorCopy Code
5. Check for service misconfigurations:

   brew services listCopy Code

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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.