How to Fix Database Collation Conflicts in WordPress

Have you ever run into WordPress errors like:

WordPress database error: Collation conflict: utf8mb4_general_ci vs utf8mb4_unicode_ci

Or experienced weird sorting behavior, broken search, or plugin malfunctions?

These are signs of a collation conflict in your WordPress database. In this guide, we’ll walk you through how to identify and fix collation conflicts to ensure your site runs smoothly and consistently.

🧠 What Is a Collation?

A collation determines how text is compared and sorted in your database.

Examples:

• utf8mb4_general_ci
• utf8mb4_unicode_ci
• latin1_swedish_ci

Even though two fields may use the same character set (e.g., utf8mb4), using different collations can cause MySQL to fail comparisons or JOINs, leading to errors or unexpected results.

❗ Common Symptoms of Collation Conflicts

• WordPress database errors in logs or frontend
• Search or sorting not working properly
• Plugin errors after migration
• Admin area misbehavior (especially with forms or filters)
• Error during WP CLI commands or multisite sync

🔍 Step 1: Detect Collation Conflicts

Option 1: Use phpMyAdmin

1. Open your database
2. Click “Structure” on each table
3. Check the Collation column — look for mixed values like:
   • utf8mb4_unicode_ci
   • utf8mb4_general_ci
   • latin1_swedish_ci

Option 2: Use SQL Query

Run this in phpMyAdmin or MySQL CLI:

SELECT TABLE_NAME, COLUMN_NAME, CHARACTER_SET_NAME, COLLATION_NAME
FROM information_schema.columns
WHERE table_schema = 'your_database_name';

This lists all columns and their collations — look for mismatches.

🔧 Step 2: Choose a Standard Collation

For modern WordPress sites, it’s recommended to use:

nginxCopyEditutf8mb4_unicode_ci

Why?

• It supports emojis and multilingual characters
• It’s WordPress’s default for years now
• It’s more accurate in sorting than _general_ci

🔄 Step 3: Convert Tables and Columns to a Single Collation

Use phpMyAdmin or run the following SQL for each table:

ALTER TABLE wp_posts CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE wp_comments CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE wp_options CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

Repeat for any other tables with mixed collations.

To convert all tables, you can generate a script or use a plugin like WP-DBManager.

⚙️ Step 4: Update wp-config.php (If Needed)

Ensure your site is also telling WordPress to use the correct charset and collation:

define('DB_CHARSET', 'utf8mb4');
define('DB_COLLATE', '');

If you leave DB_COLLATE empty, WordPress will use your database default (which should now be uniform).

🧪 Optional: Check WordPress Database Structure

Use WP-CLI to compare your database to the expected structure:

wp db check
wp db optimize

Or, for WooCommerce users:

wp wc tool run verify-database --user=admin

✅ Summary: Fixing Collation Conflicts in WordPress

🚀 Need Help Fixing Collation Issues?

Not sure where the conflicts are or worried about breaking your site?

👉 Let Servers9 fix it for you
We’ll scan your database, fix collation mismatches, and optimize your tables safely.