MySQL 1157: Table is read-only.

What is MySQL 1157: Table is read-only.

Check the file system where the MySQL data directory is located to ensure it's not mounted as read-only. Use the command `mount` to see mount options for all file systems.

Verify the permissions of the database table files in the MySQL data directory. Use `ls -l /var/lib/mysql/yourdatabasename` to list permissions and ensure the MySQL user has write permissions.

Check if the MySQL table is marked as read-only. Connect to the MySQL server using `mysql -u username -p`, then run `SHOW TABLE STATUS LIKE 'yourtablename';` Look for the `Comment` field to see if it indicates the table is read-only.

Ensure there's enough disk space on the drive where the MySQL data directory is located. Use `df -h` to check disk space usage.

Review the MySQL error log for any additional messages related to the read-only issue. The error log location varies but often found in `/var/log/mysql/error.log`. Use `tail -n 100 /var/log/mysql/error.log` to view the last 100 lines.

If the table is part of a replication setup, ensure that it is not set to be read-only due to replication rules. Query the `readonly` and `superreadonly` global variables by connecting to MySQL and running `SHOW VARIABLES LIKE 'readonly';` and `SHOW VARIABLES LIKE 'superreadonly';`.

For InnoDB tables, check if there's an ongoing ALTER TABLE operation or a metadata lock that might cause the table to be read-only temporarily. Connect to MySQL and run `SHOW ENGINE INNODB STATUS\G` and `SHOW FULL PROCESSLIST;` to investigate.

Attempt to flush the table if it's safe to do so, which can sometimes clear unexpected states. Connect to MySQL and run `FLUSH TABLES yourtablename;`.

Each step is directly actionable and should be executed in an environment where the user has the necessary permissions to perform system and MySQL commands.