MySQL Failed to Start? Seven Reasons Behind the Error and How to Fix Them

MySQL Failed to Start? Seven Reasons Behind the Error and How to Fix Them

When trying to start the MySQL server, you must have come across this error message:

Code:
[FAIL] Starting MySQL database server: mysqld . . . . . . . . . . . . . . failed
If you don’t know why this happens, it can be quite infuriating. And this is one of those errors that requires immediate attention. In this article, learn seven reasons why this error occurs and how you can fix them.

Why MySQL Server Fails to Start?

There are more than one reasons behind MySQL failing to start. If you want to fix this issue, you must be aware of all of the reasons.
  • Configuration Errors – If there are errors in the configuration file at /etc/my.cnf, the MySQL server may fail to start. MySQL stores all the information related to configurations at this place. You must ensure that it exists and is free from errors.
  • Corrupted MySQL binary – If the MySQL binary (a set of log files) or tables get corrupt, MySQL server will fail to start.
  • Insufficient permission and ownership for binaries and folders – The MySQL binaries and folders are granted a set of permissions regarding who can and cannot access them. There are times when ownership and permission details for the /var/lib/mysql folder get changed. You must correct these changes.
  • The MySQL port is in use – There’s a chance that the default MySQL port which is set to 3306 is already in use. In that case, MySQL would fail to bind to the port.
  • /tmp directory not writable – If MySQL is not able to write to the /tmp directory, then the server won’t start. This can happen because of permission issues or lack of space in the folder.
  • Disk space is full – If the server lacks sufficient space, then MySQL will fail to start. Make sure you have enough disk space available. You can check that using df -h command.
  • Memory is full – Similarly, if memory is full, MySQL will not enough space to run. So it’ll either stop or crash midway every time you try to run it.

How to Fix the Issue?

Just like there are more than one reasons behind this error, there are multiple ways to fix the issue. Here are some solutions you should try:

  • Set appropriate permission – You need to make sure that MySQL can access all the necessary files and folders. Therefore, set the correct permission at all levels. Ensure that mysql user can read and modify them at will.
  • Allocate more disk space – If you’re running out of disk space, consider removing certain files and folders to make some room. Or you can move the data to a different partition or to a backup server instead of deleting.
  • Correct the configuration errors – If there are errors in the my.cnf file, you need to resolve them first.
  • Add more swap memory – If you do not have sufficient memory on the server, then consider allocating more swap memory.
  • Check the error logs – Error log will get you the exact reason behind the issue. Check and pin point the issue and take measures to fix them. In MySQL, the errors are stored in the hostname.err file.
  • Reinstall the server – Reinstalling the server can solve the issue in some cases. If the previous installation was incomplete, then installing the MySQL server is a best solution. It also fixes any corrupt MySQL binary that might exist on the server.
So these are some of the ways you can fix the ‘MySQL Failed to Start’error.
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