Blueprint.php

<?php namespace Acme\Database;

use Illuminate\Database\Schema\Blueprint as BaseBlueprint;

class Blueprint extends BaseBlueprint {}

MysqlConnection.php

<?php namespace Acme\Database;

use Illuminate\Database\MysqlConnection as BaseMysqlConnection;
use Illuminate\Database\Schema\MysqlBuilder;

class MysqlConnection extends BaseMysqlConnection
{

	/**
	 * Get a schema builder instance for the connection.
	 *
	 * @return \Illuminate\Database\Schema\MySqlBuilder
	 */
	public function getSchemaBuilder()
	{
		if (is_null($this->schemaGrammar)) { $this->useDefaultSchemaGrammar(); }

		return new MySqlBuilder($this)->blueprintResolver(function($table, $callback) {
			return Blueprint( $table, $callback ); // return our custom Blueprint class
		});
	}

	/**
	 * Get the default schema grammar instance.
	 *
	 * @return \Illuminate\Database\Schema\Grammars\MySqlGrammar
	 */
	protected function getDefaultSchemaGrammar()
	{
		return $this->withTablePrefix(new SchemaGrammar); // return our custom SchemaGrammer
	}

}

MysqlGrammer.php

<?php namespace Acme\Database;

use Illuminate\Database\Schema\Grammars\MySqlGrammar

class SchemaGrammer extends MysqlGrammer
{

}

start.php

<?php

// This can (and most likely should) be in a Service Provider

App::bind('db.connection.mysql', 'Acme\Database\MysqlConnection');

i get the same issue here for Laravel 5.6, any update please, thank you.