Error
Error Code:
15
MySQL Error 15: Can't Open Stream Handle
Description
MySQL Error 15 indicates that the server attempted to open a file or stream using an operating system handle but failed. This error typically points to underlying OS-level issues, such as incorrect file permissions, a locked resource, or an invalid file path, preventing MySQL from accessing necessary resources like data files, log files, or temporary files.
Error Message
Can't open stream from handle (OS errno %d - %s)
Known Causes
4 known causesIncorrect File Permissions
The MySQL server process lacks the necessary read or write permissions for a file or directory it's attempting to access, such as data files, log files, or temporary files.
File or Resource Locked
An external application or another MySQL process might have an exclusive lock on the file or resource that MySQL is trying to open, preventing access.
Invalid Path or Missing File
MySQL is configured to access a file or directory that does not exist at the specified path, or the path itself is incorrectly formatted in the configuration.
Operating System Resource Limits
The operating system has reached its maximum limit for open file handles or other resources, preventing MySQL from opening new streams or files.
Solutions
4 solutions available1. Verify File/Directory Permissions medium
Ensures the MySQL user has read/write access to necessary files and directories.
1
Identify the file or directory that MySQL is trying to access. This is often indicated in the MySQL error log or by the context of the operation failing (e.g., data directory, log file, temporary directory).
2
Determine the user under which the MySQL server is running. You can usually find this in the MySQL configuration file (e.g., `my.cnf` or `my.ini`) or by checking the process owner with `ps aux | grep mysqld` (on Linux/macOS).
ps aux | grep mysqld3
Using the identified file/directory and MySQL user, check and adjust permissions. For example, if the data directory `/var/lib/mysql` is causing issues and MySQL runs as user `mysql`:
sudo chown -R mysql:mysql /var/lib/mysql
sudo chmod -R 755 /var/lib/mysql4
Repeat this for any other files or directories that might be involved, such as log files, socket files, or temporary directories specified in your MySQL configuration.
5
Restart the MySQL server to apply the permission changes.
sudo systemctl restart mysql2. Check for Disk Space Issues easy
Confirms that the disk where MySQL stores its data or logs is not full.
1
Check the available disk space on the partitions where MySQL data, logs, and temporary files are stored. This is often the `datadir` and `log_error` specified in your MySQL configuration.
df -h2
If any of the relevant partitions are at or near 100% capacity, free up disk space by deleting unnecessary files or expanding the storage.
3
After freeing up space, restart the MySQL server.
sudo systemctl restart mysql3. Investigate File System Corruption advanced
Addresses potential underlying file system problems that prevent MySQL from accessing files.
1
Stop the MySQL server gracefully.
sudo systemctl stop mysql2
Run a file system check on the partition where MySQL data resides. The command varies by OS and file system type (e.g., `fsck` for ext4/ext3, `xfs_repair` for XFS). It's often best to run this from a recovery environment or with the partition unmounted.
sudo fsck -yf /dev/sdXY # Replace /dev/sdXY with your partition3
If file system errors are found and repaired, restart the MySQL server.
sudo systemctl start mysql4
If the issue persists, consider restoring MySQL data from a backup to a known good state, as severe file system corruption might necessitate this.
4. Review MySQL Configuration for Invalid Paths medium
Ensures that all paths defined in the MySQL configuration file are valid and accessible.
1
Locate your MySQL configuration file (e.g., `/etc/mysql/my.cnf`, `/etc/my.cnf`, `/etc/mysql/mysql.conf.d/mysqld.cnf`).
2
Open the configuration file and carefully examine paths defined for parameters like `datadir`, `log_error`, `pid-file`, `socket`, `tmpdir`, and any plugin directories.
[mysqld]
datadir = /var/lib/mysql
log_error = /var/log/mysql/error.log
socket = /var/run/mysqld/mysqld.sock3
Verify that each of these directories/files actually exists and that the MySQL user (as identified in Solution 1) has appropriate permissions to access them.
4
Correct any typos, incorrect paths, or non-existent directories. Ensure that the specified directories are created if they are missing.
5
Save the configuration file and restart the MySQL server.
sudo systemctl restart mysql