requires ext-fileinfo. How do I add that into my composer.json file?

For new versions. In my case it in here.

Let search this key extension=fileinfo to find it in php.ini file. My php version 7.3.32

Nothing to do with your composer.json.

You need to install & enable FileInfo PHP extension, which is installed by default starting with PHP 5.3.0. Versions prior to 5.3+ may use the discontinued PECL extension.

To enable FileInfo extension, you need to edit your php.ini and change a single line.

1. Locate the line:

   ;extension=php_fileinfo.dll
   

2. Remove the starting comment:

   extension=php_fileinfo.dll
   

---

To find out where your php.ini is located, you can run the following command from a terminal:

$ php --ini

and search for "Loaded Configuration File".

Please note that the PHP CLI can load a different php.ini file than the web, so don't rely on the path provided in phpinfo(). Run the command specified above in a terminal to find out the file loaded by PHP CLI.

We dont need to do anything in composer.json

Windows

Enable fileinfo extension in php.ini

extension= php_fileinfo.dll

In Linux

1) Download and untar the package

wget http://pecl.php.net/get/Fileinfo-1.0.4.tgz

tar -zxf Fileinfo-1.0.4.tgz

cd Fileinfo-1.0.4

2) Generate the extension for compiling

phpize

3) Configure the module

./configure

4) generate the install files and install it

make

make install

5) Now the extension will be available under the /usr/lib64/php/modules directory. You now need to add the extension somewhere in the php configuration file. Edit /etc/php.ini and add the following: extension=fileinfo.so 6) Save the file and restart the webserver

service httpd restart

To verify fileinfo module is enabled properly, execute:

php -i | grep fileinfo

fileinfo support => enabled

Alternate method

Just an FYI, the module can also be installed using the PECL command i.e.

pecl install fileinfo

Once done, just follow steps 5 and 6 mentioned above to enable it. That’s it.

If anyone else is on DreamHost (like me) or finds that the php.ini edits don't do what you want, you can try another route.

Here's the DreamHost Wiki page on PHP.ini, but I'll list the steps below as well.

Step 1: Create a PHP configuration file (phprc)

1. In your user's home folder (/home/your_user_name), create a new folder called .php (notice the leading period)
2. Inside this new folder, create another folder based on the version of PHP that you're using. You can find this (and change it) on the hosting panel (DreamHost's is at panel.dreamhost.com under Domains > Manage Domains). So if you're using PHP version 5.6, create a folder called 5.6.
3. Inside this new folder, create a new file called phprc (no extension). If there's already a phprc file in this folder, you can back it up by changing the filename to phprc.old.

Step 2: Edit phprc to include the extension

1. Open your new phprc file.
2. Add this line to the end: extension = fileinfo.so
3. Save the file

Step 3: Restart PHP and/or your web server

Via Panel

If you have shared hosting, or you aren't comfortable with SSH or the command line, you can force DreamHost to pick up your new phprc settings.

1. Navigate back to your Panel, and go to Domains > Manage Domains.
2. Click Edit next to the domain you're working on.
3. Don't make any changes here. Simply scroll down and click at the bottom of the first section.
4. Within about 10 minutes, DreamHost will pull in your changes.
5. If you don't see updates after 10 minutes (be patient!), contact support for help.

Via SSH

If you're comfortable with the command line (and you're not using shared hosting), SSH into your server and run the following commands:

For Apache web servers

sudo /etc/init.d/httpd2 restart

For Nginx web servers

sudo /etc/init.d/nginx stop
pkill -9 php
sudo /etc/init.d/nginx start

Your specific commands may be slightly different, but if you're comfortable with CLI then you probably know your specific command.