1. Find out which php.ini is used.

2. In file php.ini this line:

   extension=mysqli
   

3. Replace by:

   extension="C:phpextphp_mysqli.dll"
   

4. Restart apache

If your configuration files are okay but still having the same issue then install php7.x-mysql according to the version of the installed php.

For example in my case, I’m using php7.3 so I ran the following command to get it all set:

sudo apt install php7.3-mysql

systemctl reload apache2

I know this is a while ago but I encountered this and followed the other answers here but to no avail, I found the solution via this question (Stackoverflow Question)

Essentially just needed to edit the php.ini file (mine was found at c:xamppphpphp.ini) and uncomment these lines…

;extension=php_mysql.dll
;extension=php_mysqli.dll
;extension=php_pdo_mysql.dll

After restarting apache all was working as expected.

• In your Xampp folder, open php.ini file inside the PHP folder i.e xamppphpphp.ini (with a text editor).

• Search for extension=mysqli (Ctrl+F), if there are two, look for the one that has been uncommented (without “;” behind)

• Change the mysqli with the correct path address i.e extension=C:xamppphpextphp_mysqli.dll.

• On your Xampp control panel, stop and start apache and MySQL

sudo apt-get install php7.2-mysql

extension=mysqli.so (add this php.ini file)

sudo service apache2 restart

Please use above commands to resolve mysqli-extension missing error

Simply specify the directory in which the loadable extensions (modules) reside in the php.ini file from

; On windows:
extension_dir="C:xamppphpext"

to

; On windows:
;extension_dir = "ext"

Then enable the extension if it was disabled by changing

;extension=mysqli

to

extension=mysqli

This article can help you Configuring PHP with MySQL for Apache 2 or IIS in Windows. Look at the section “Configure PHP and MySQL under Apache 2”, point 3:

extension_dir = "c:phpextensions"      ; FOR PHP 4 ONLY 
extension_dir = "c:phpext"             ; FOR PHP 5 ONLY

You must uncomment extension_dir param line and set it to absolute path to the PHP extensions directory.

Copy libmysql.dll from the PHP installation folder to the windows folder.

I’ve been searching for hours and no one could help me. I did a
simple thing to solve this problem. (WINDOWS 10 x64)

Follow this:

1 – Go to your php_mysqli.dll path (in my case: C:/xampp/php/ext);

2 – Move the php_mysqli.dll to the previous folder (C:/xampp/php);

3 – Open php.ini and search the line: “extension: php_mysqli.dll”;

4 – Change to the path where is your file: extension=”C:xamppphpphp_mysqli.dll”;

5 – Restart your application (wampp, xampp, etc.) and start Apache Server;

The problem was the path ext/php_mysqli.dll, I’ve tried changing the line to extension=”C:xamppphpextphp_mysqli.dll” but doesn’t worked.

I had the same problem and I solved it. You can solve it too if you follow these steps:

1. you have to install PHP to C:/php
   or your current version locate it to this path and specify it as a system variable

2. then open xampp program and click config and open php.ini
   and uncomment the following lines:

   extension=pdo_mysql
   extension=pdo_mysql
   extension=openssl
   

try to change PHP version

$sudo update-alternatives --config php

if it didn’t work
change for example from PHP 5.6 => PHP 7.1

    $ sudo a2dismod php5.6
    $ sudo a2enmod php7.1  
    $ sudo service apache2 restart

I encountered this problem today and eventually I realize it was the comment on the line before the mysql dll’s that was causing the problem.

This is what you should have in php.ini by default for PHP 5.5.16:

;extension=php_exif.dll       Must be after mbstring as it depends on it
;extension=php_mysql.dll
;extension=php_mysqli.dll

Besides removing the semi-colons, you also need to delete the line of comment that came after php_exif.dll. This leaves you with

extension=php_exif.dll      
extension=php_mysql.dll
extension=php_mysqli.dll

This solves the problem in my case.

I simply copied my php_myslqli.dll file from ert folder back to php folder, and it worked for me after restarting my Apache and MySQL from the control Panel

Its an issue of extension directory. You need to change php extension directory manually to work this.

If you are using AMPP Server, do the following

Goto settings -> PHP -> Configuration

in php7.3.ini Find, (Versions might change)

extension_dir = “” , (Already having some path)

and change value to

extension_dir = “C:Program FilesAmppsphp-7.3ext”

If you are using XAMP

Goto XAMP Settings, Apache -> PHP.ini

Find, extension_dir = in php.ini, and set path of the php extension folder of your local machine. See the below example.

extension_dir = “C:phpext” (Check your path properly)

In my case, I had a similar issue after full installation of Debian 10.

Commandline:
php -v show I am using php7.4 but print phpinfo() gives me php7.3

Solution: Disable php7.3 Enable php7.4

   $ a2dismod php7.3
    
   $ a2enmod php7.4
    
   $ update-alternatives --set php /usr/bin/php7.4
   $ update-alternatives --set phar /usr/bin/phar7.4
   $ update-alternatives --set phar.phar /usr/bin/phar.phar7.4
   $ update-alternatives --set phpize /usr/bin/phpize7.4
   $ update-alternatives --set php-config /usr/bin/php-config7.4

Replace

include_path=C:Program Files (x86)xamppphpPEAR

with following

include_path="C:Program Files (x86)xamppphpPEAR"

i.e Add commas , i checked apache error logs it was showing syntax error so checked whole file for syntax errors.

The thing that fixed my problem is: open php.ini then add this extension=php_mysqli.dll

for linux users

For me it was a weird behavior:
i went to phpmyadmin directory (for me /usr/share/phpmyadmin) and inside index.php file entered phpinfo();, then refreshed phpmyadmin web page;

surprisingly phpmyadmin was using different php version than what set on system. event update-alternatives --config php doesn’t change situation;

so i just disabled all other php version using directly a2dismod php8.1 (and whatever version you have) command and then enabled a version via a2enmod command.

hope help someone;