[Error] 
Using $this when not in object context (0)
/home/bitrix/www/bitrix/modules/main/classes/general/user.php:2147
#0: CAllUser::Update(integer, array)
	/home/bitrix/www/local/functions/CustomAgents.php:91
#1: CustomAgents::activateUsersAgent()
	/home/bitrix/www/bitrix/modules/main/classes/mysql/agent.php(163) : eval()'d code:1
#2: eval
	/home/bitrix/www/bitrix/modules/main/classes/mysql/agent.php:163
#3: CAgent::ExecuteAgents(string)
	/home/bitrix/www/bitrix/modules/main/classes/mysql/agent.php:40
#4: CAgent::CheckAgents()
	/home/bitrix/www/bitrix/modules/main/include.php:263
#5: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog_before.php:14
#6: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog.php:10
#7: require_once(string)
	/home/bitrix/www/bitrix/header.php:1
#8: require(string)
	/home/bitrix/www/students/index.php:2
#9: include_once(string)
	/home/bitrix/www/bitrix/modules/main/include/urlrewrite.php:159
#10: include_once(string)
	/home/bitrix/www/bitrix/urlrewrite.php:2