Unable to connect to the database.

Hii i have changed the threshold value to 4 and created a log file of today's . I am adding it below
Code:

Code:

CRITICAL - 2020-08-11 10:53:58 --> Unable to connect to the database.

#0 /opt/lampp/htdocs/ignite4/system/Database/BaseConnection.php(646): CodeIgniter\Database\BaseConnection->initialize()

#1 /opt/lampp/htdocs/ignite4/system/Database/BaseBuilder.php(1860): CodeIgniter\Database\BaseConnection->query()

#2 /opt/lampp/htdocs/ignite4/system/Model.php(462): CodeIgniter\Database\BaseBuilder->get()

#3 /opt/lampp/htdocs/ignite4/app/Models/NewsModel.php(12): CodeIgniter\Model->findAll()

#4 /opt/lampp/htdocs/ignite4/app/Controllers/News.php(13): App\Models\NewsModel->getNews()

#5 /opt/lampp/htdocs/ignite4/system/CodeIgniter.php(918): App\Controllers\News->index()

#6 /opt/lampp/htdocs/ignite4/system/CodeIgniter.php(404): CodeIgniter\CodeIgniter->runController()

#7 /opt/lampp/htdocs/ignite4/system/CodeIgniter.php(312): CodeIgniter\CodeIgniter->handleRequest()

#8 /opt/lampp/htdocs/ignite4/public/index.php(45): CodeIgniter\CodeIgniter->run()

#9 /opt/lampp/htdocs/ignite4/system/Commands/Server/rewrite.php(34): require_once('/opt/lampp/htdo...')

#10 {main}

ERROR - 2020-08-11 10:55:33 --> Error connecting to the database:
Call to undefined function CodeIgniter\Database\MySQLi\mysqli_init()

CRITICAL - 2020-08-11 10:55:33 --> Unable to connect to the database.

#0 /opt/lampp/htdocs/ignite4/system/Database/BaseConnection.php(646): CodeIgniter\Database\BaseConnection->initialize()

#1 /opt/lampp/htdocs/ignite4/system/Database/BaseBuilder.php(1860): CodeIgniter\Database\BaseConnection->query()

#2 /opt/lampp/htdocs/ignite4/system/Model.php(462): CodeIgniter\Database\BaseBuilder->get()

#3 /opt/lampp/htdocs/ignite4/app/Models/NewsModel.php(12): CodeIgniter\Model->findAll()

#4 /opt/lampp/htdocs/ignite4/app/Controllers/News.php(13): App\Models\NewsModel->getNews()

#5 /opt/lampp/htdocs/ignite4/system/CodeIgniter.php(918): App\Controllers\News->index()

#6 /opt/lampp/htdocs/ignite4/system/CodeIgniter.php(404): CodeIgniter\CodeIgniter->runController()

#7 /opt/lampp/htdocs/ignite4/system/CodeIgniter.php(312): CodeIgniter\CodeIgniter->handleRequest()

#8 /opt/lampp/htdocs/ignite4/public/index.php(45): CodeIgniter\CodeIgniter->run()

#9 /opt/lampp/htdocs/ignite4/system/Commands/Server/rewrite.php(34): require_once('/opt/lampp/htdo...')

#10 {main}