Fixing MySQL Import Errors in WordPress Database Migration: Version and Character Set Compatibility

Common WordPress Database Migration Errors and Solutions

During WordPress site migration or database import, failures often occur due to inconsistencies between the source and target MySQL versions, character sets, or collations. This article provides clear troubleshooting and resolution steps for typical SQL syntax errors and unknown collation errors.

Common Error Types and Causes

Migration errors generally fall into two categories:

• SQL Syntax Errors: For example, ERROR 1064 (42000). This usually happens because the exported SQL file contains syntax from an older MySQL version (like TYPE=MyISAM) that is no longer supported by the newer MySQL version on the target server.
• Unknown Collation Errors: For example, ERROR 1273 (HY000): Unknown collation: 'utf8mb4_unicode_ci'. This occurs when the source database uses a newer character set (like utf8mb4) whose collation is not supported by the target MySQL version (e.g., 5.5 or earlier).

Error 1: SQL Syntax Error (TYPE=MyISAM)

Example error:

ERROR 1064 (42000) at line 28: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'TYPE=MyISAM AUTO_INCREMENT=1' at line 9

Cause: In MySQL 5.5 and later, the TYPE=MyISAM syntax is deprecated and should be replaced with ENGINE=MyISAM.

Solution:

1. Open the exported .sql file in a text editor (e.g., Notepad++, VS Code).
2. Find and replace all instances of TYPE=MyISAM with ENGINE=MyISAM.
3. Save the file and attempt the import again.

Error 2: Unknown Collation (utf8mb4_unicode_ci)

Example error:

ERROR 1273 (HY000) at line 29: Unknown collation: 'utf8mb4_unicode_ci'

Cause: The utf8mb4 character set and its corresponding collations were introduced in MySQL 5.5.3. If the target MySQL version is older (e.g., 5.1), it will not recognize them.

Solution: Use a text editor to perform a batch find-and-replace on the character set and collation definitions in the SQL file. Follow this order to avoid incomplete replacements or new errors:

1. Replace all instances of utf8mb4_unicode_ci with utf8_general_ci.
2. Replace all instances of utf8mb4 with utf8.
3. (Optional) If the file contains CHARSET=utf8mb4, also replace it with CHARSET=utf8.

Important Notes:

• Always use an editor that supports UTF-8 encoding to avoid file corruption.
• Back up the original SQL file before making changes.
• After replacement, re-import using the command: mysql -u username -p database_name < file.sql.

Prevention and Best Practices

To avoid compatibility issues during migration, consider these measures:

• Standardize Environments: Try to keep the major MySQL version consistent across development, testing, and production environments.
• Use Modern Versions: For new WordPress deployments, use MySQL 5.6 or later to natively support the utf8mb4 character set (which can store 4-byte emojis).
• Use Professional Migration Plugins: For WordPress sites, use dedicated plugins like All-in-One WP Migration or Duplicator, which often handle underlying database compatibility issues.
• Specify Compatibility Options on Export: When using the mysqldump command, you can add parameters like --compatible=mysql40 to generate a more compatible SQL file (though some newer features may be lost).

Following these methods should resolve most WordPress database import errors caused by version differences. If problems persist, check database user permissions and ensure the target database was created successfully.