Laravel foreign key onDelete('cascade') not working

Try setting when trying to create this table. This fix has worked for me.

$table->engine = 'InnoDB';

I have filed a bug under: https://github.com/laravel/framework/issues/8730

It is established by Jake's answer that you have set default engine to InnoDB

$table->engine = 'InnoDB';

Instead of doing it in each migration file, You can do so in config/database.php

'mysql' => [
        'driver' => 'mysql',
        'host' => env('DB_HOST', '127.0.0.1'),
        'port' => env('DB_PORT', '3306'),
        'database' => env('DB_DATABASE', 'forge'),
        'username' => env('DB_USERNAME', 'forge'),
        'password' => env('DB_PASSWORD', ''),
        'unix_socket' => env('DB_SOCKET', ''),
        'charset' => 'utf8mb4',
        'collation' => 'utf8mb4_unicode_ci',
        'prefix' => '',
        'strict' => false,
        'engine' => 'InnoDB',
    ],

Check the MySQL config. my.ini may still have default-storage-engine=MYISAM. Set to default-storage-engine=InnoDB and you should avoid the trouble of adding this fix to each migration.