What to put in php_value auto_prepend_file in Joomla?

Question

PHP

I set general settings on the PHP server php_value auto_prepend_file so Bitrix wanted
The site on Bitrix works successfully when I added a line to the .htaccess file as Bitrix wrote
php_value auto_prepend_file "/home/www//bitrix/modules/security/tools/start.php"

On There are also two more sites on Joomla on the server, they refuse to work, I see a white screen

. There are no entries in the error logs for sites. Enabling the debug mode using CMS tools also does not result in any errors.

Help, please, where is the dog buried?
What entry should I add to Joomla sites in .htaccess to make them work?
I will be grateful!)