"Cannot load DB manager" on new 7.12.2 SuiteCRM

I have AlmaLinux 8.5 machine.
On that I installed Nginx, PHP and MariaDB according to instructions here

I was also consulting Downloading & Installing :: SuiteCRM Documentation for installation.
Everything went well until I opened http://MyServer.com/suitecrm/install.php in my browser.
After accepting license and checking all OKs in System environment preview I came to Database Configuration. I selected MySQL (mysqli extension) and provided data for Database Name & SuiteCRM Database User + password. I Also defined admin user.
When I click NEXT button I ALWAYS get “Cannot load DB manager” no matter what I changed and I changed A LOT.
I Googled “Cannot load DB manager” and tried everything found on this forum and elsewhere. Nothing helped.
The error in /etc/var/log/nginx/suite_crm.log is:

2021/12/28 13:15:13 [error] 74746#0: *139 FastCGI sent in stderr: “PHP message: PHP Warning: Undefined array key “setup_db_type” in /var/www/html/suitecrm/install/install_utils.php on line 587 PHP message: PHP Warning: Undefined array key “setup_db_manager” in /var/www/html/suitecrm/install/install_utils.php on line 587 PHP message: PHP Fatal error: Uncaught Exception: Cannot load DB manager in /var/www/html/suitecrm/include/utils.php:1920
Stack trace:
#0 /var/www/html/suitecrm/include/database/DBManagerFactory.php(100): sugar_die()
#1 /var/www/html/suitecrm/install/install_utils.php(587): DBManagerFactory::getTypeInstance()
#2 /var/www/html/suitecrm/install/checkDBSettings.php(320): getInstallDbInstance()
#3 /var/www/html/suitecrm/install/checkDBSettings.php(53): copyInputsIntoSession()
#4 /var/www/html/suitecrm/install.php(356): checkDBSettings()
#5 {main}
thrown in /var/www/html/suitecrm/include/utils.php on line 1920” while reading response header from upstream, client:, server: MyServer.com, request: “POST /suitecrm/install.php HTTP/1.1”, upstream: “fastcgi://unix:/var/run/php-fpm/www.sock:”, host: “MyServer.com”, referrer: “http://MyServer.com/suitecrm/install.php
What could be wrong here?
Any idea would be greatly appreciated.

I suspect that you have warnings outputting to stderr rather than to a error.log. Outputting it to standard output will cause the "while reading response header from upstream, " because the output was sent to the browser before it should’ve. Have a look to getting your error messages from the server into a logging file and try again. :+1: