🇷🇺Russia @ru.bsv

Other error message for the same problem:

PHP Fatal error: Uncaught TypeError: Drupal\Core\Database\Connection::getClientConnection(): Return value must be of type object, null returned in /.../web/core/lib/Drupal/Core/Database/Connection.php:306 Stack trace: 
#0 /.../web/core/modules/mysql/src/Driver/Database/mysql/TransactionManager.php(31): Drupal\Core\Database\Connection->getClientConnection() 
#1 /.../web/core/lib/Drupal/Core/Database/Transaction/TransactionManagerBase.php(278): Drupal\mysql\Driver\Database\mysql\TransactionManager->processRootCommit() 
#2 /.../web/core/lib/Drupal/Core/Database/Transaction.php(88): Drupal\Core\Database\Transaction\TransactionManagerBase->unpile() 
#3 [internal function]: Drupal\Core\Database\Transaction->__destruct() 
#4 {main} 
  thrown in /.../web/core/lib/Drupal/Core/Database/Connection.php on line 306

I'm using:

• Drupal version: 10.2.0
• PHP version: 8.1.27
• Drush version: 12.4.3.0

I fixed the problem with (the temporary way).

1. Check whether the Xdebug is installed:
php -m | grep Xdebug

2. Disabled Xdebug:
sudo mv /etc/php/8.1/mods-available/xdebug.ini /etc/php/8.1/mods-available/xdebug.ini.bak
sudo systemctl restart nginx php8.1-fpm

check whether the Xdebug is not installed:
php -m | grep Xdebug

drush updatedb -y
Successfully!

ru.bsv → created an issue.