Laravel 5.4 and higher version ( Specified key was too long when doing migration)

Specify a smaller length for your e-mail:

$table->string('email', 250);

Which is the default, actually:

$table->string('email');

And you should be good.

For Laravel 5.4 you can find a solution in this Laravel 5.4: Specified key was too long error, Laravel News post:

As outlined in the Migrations guide to fix this all you have to do is edit your AppServiceProvider.php file and inside the boot method set a default string length:

namespace App\Providers;

use Illuminate\Support\Facades\Schema;
use Illuminate\Support\ServiceProvider;
public function boot()
{
    Schema::defaultStringLength(191);
}

Soure :

https://stackoverflow.com/questions/23786359/laravel-migration-unique-key-is-too-long-even-if-specified