[ErrorException] E_NOTICE
Undefined index: user (0)
/home/bitrix/www/bitrix/modules/main/lib/web/uri.php:46
#0: Bitrix\Main\Web\Uri->__construct(string)
	/home/bitrix/www/bitrix/modules/main/lib/httprequest.php:252
#1: Bitrix\Main\HttpRequest->getRequestedPage()
	/home/bitrix/www/bitrix/modules/main/lib/request.php:72
#2: Bitrix\Main\Request->getRequestedPageDirectory()
	/home/bitrix/www/bitrix/modules/main/lib/request.php:80
#3: Bitrix\Main\Request->isAdminSection()
	/home/bitrix/www/bitrix/modules/main/include.php:70
#4: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog_before.php:14
#5: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog.php:10
#6: require_once(string)
	/home/bitrix/www/bitrix/header.php:1
#7: require(string)
	/home/bitrix/www/contacts/uchebnyy-klass/index.php:1