If you’re encountering the “ERROR 1273 (HY000): Unknown collation: ‘utf8mb4_unicode_520_ci‘” issue, it’s likely because your MySQL or MariaDB server does not support the utf8mb4_unicode_520_ci collation. This collation was introduced in MySQL 5.7.6 and may not be available on older versions or certain MariaDB versions.

Here’s how you can resolve this issue:

Identify Unsupported Collation: Check which collation is causing the issue by examining your SQL file. Open the file in a text editor and look for instances of utf8mb4_unicode_520_ci.

Replace with Supported Collation: Replace utf8mb4_unicode_520_ci with utf8mb4_unicode_ci or another compatible collation. This can often be done using a find-and-replace feature in your text editor:

utf8mb4_unicode_520_ci ➔ utf8mb4_unicode_ci
Save and Re-import: After making the changes, save the file and try re-importing it into your database.

Alternative Solution Using Command Line: You can also specify the default collation when creating the database.
For example:

CREATE DATABASE your_database_name CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

Upgrade MySQL/MariaDB Version (if possible): Consider updating to a more recent version of MySQL or MariaDB that supports utf8mb4_unicode_520_ci if it is essential for your project.

By following these steps, you should be able to resolve the collation error and proceed with your database import or migration.