string(1) "s"
<pre>[RuntimeException] 
Could not start session because headers have already been sent. &quot;/home/web/vm-12fb2dc0.na4u.ru/www/404.php&quot;:6. (0)
/home/web/vm-12fb2dc0.na4u.ru/www/bitrix/modules/main/lib/session/session.php:151
#0: Bitrix\Main\Session\Session-&gt;start()
	/home/web/vm-12fb2dc0.na4u.ru/www/bitrix/modules/main/lib/session/kernelsessionproxy.php:47
#1: Bitrix\Main\Session\KernelSessionProxy-&gt;start()
	/home/web/vm-12fb2dc0.na4u.ru/www/bitrix/modules/main/include.php:185
#2: require_once(string)
	/home/web/vm-12fb2dc0.na4u.ru/www/bitrix/modules/main/include/prolog_before.php:19
#3: require(string)
	/home/web/vm-12fb2dc0.na4u.ru/www/404.php:8
#4: include_once(string)
	/home/web/vm-12fb2dc0.na4u.ru/www/bitrix/urlrewrite.php:4
----------
</pre>