Laravel - error on migrate

PHP 5.6
Mysql 5.5
Laravel 5.4


I had this error while executing: php artisan migrate

Syntax error or access violation: 1071 Specified key was too long; max key l ength is 767 bytes (SQL: alter table `users` add unique `users_email_unique`(`email`))

I solved by changing the file config/database.php:

'charset' => 'utf8mb4' by 'charset' => 'utf8'

'collation' => 'utf8mb4_unicode_ci' by 'collation' => 'utf8_unicode_ci'

Drop the created tables by laravel, and execute php artisan migrate again.