How to Install PHP on Ubuntu and Run Multiple Versions (ondrej/php PPA, update-alternatives, and PHP-FPM per Site)

Short answer: Ubuntu's own repositories ship one PHP version per release (PHP 8.3 on Ubuntu 24.04, PHP 8.1 on 22.04). To get a different version, or several at once, add Ondřej Surý's PPA with sudo add-apt-repository ppa:ondrej/php, run sudo apt update, and install versioned packages such as php8.4-fpm php8.4-cli php8.4-mysql. Every version installs into its own /etc/php/<version>/ directory and runs its own PHP-FPM service and socket, so versions don't conflict. Pick the version the php command uses with sudo update-alternatives --config php. For each Nginx site, set fastcgi_pass to the socket of the version that site needs.

Why Install a Specific PHP Version on Ubuntu?

Most people end up here for one of three reasons:

• Your app needs a newer PHP than Ubuntu ships. For example, a new Laravel or Symfony release requires a version that your LTS release doesn't have yet.
• A legacy app needs an older PHP. You need to keep it running while you migrate it, without holding back every other site on the server.
• You're setting up a local development environment and want to match production exactly.

Ubuntu's default php package always points to the release's single bundled version. It doesn't give you a choice. The ondrej/php PPA is the standard way around this. It's maintained by Ondřej Surý, who also maintains PHP packaging for Debian, and it provides many PHP versions built for current Ubuntu LTS releases. You can install them side by side.

One warning before you start: don't install end-of-life PHP for new work. Older tutorials still tell you to install PHP 7.4, but PHP 7.4 reached end of life in November 2022 and gets no security fixes. Check php.net/supported-versions for the current list and use a supported branch wherever you can.

Prerequisites

• Ubuntu 24.04 or 22.04 with a sudo user
• Nginx installed if you're serving sites (how to install Nginx on Ubuntu)
• The PHP version your app requires (check its composer.json under require.php)

This guide uses PHP 8.4 as the "new" version and PHP 8.2 as the "legacy" version. Swap in whichever versions you need. The commands are the same.

Step 1: Check Which PHP Version Is Installed

php -v                     # CLI version (if any PHP is installed)
ls /etc/php/               # one directory per installed version
ls /run/php/               # FPM sockets for running versions
apt policy php             # which version Ubuntu's default "php" package points to

If /etc/php/ already contains a version, it stays installed. Adding the PPA doesn't remove it. It only makes more versions available.

Step 2: Add the ondrej/php PPA

sudo apt update
sudo apt install -y software-properties-common ca-certificates
sudo add-apt-repository ppa:ondrej/php
sudo apt update

To see the versions you can now install:

apt-cache search --names-only '^php[0-9.]+-fpm$'

On Debian, use Ondřej's repository at packages.sury.org instead of the PPA. The package names are the same.

Step 3: Install PHP-FPM, the CLI, and Extensions

Install the FPM and CLI packages explicitly:

sudo apt install -y php8.4-fpm php8.4-cli php8.4-common \
  php8.4-mysql php8.4-mbstring php8.4-xml php8.4-curl \
  php8.4-zip php8.4-bcmath php8.4-intl php8.4-gd

This matters. If you install the bare php8.4 metapackage, apt can pull in Apache and libapache2-mod-php8.4 to satisfy its dependencies. On an Nginx server you want php8.4-fpm, not the Apache module.

To add the legacy version alongside it, run the same command with the other version number. Brace expansion keeps it short:

sudo apt install -y php8.2-{fpm,cli,common,mysql,mbstring,xml,curl,zip,bcmath,intl,gd}

Common PHP Extensions and What Uses Them

Package	Provides	Typically needed by
phpX.Y-fpm	FastCGI Process Manager	Any site behind Nginx
phpX.Y-cli	The phpX.Y command	Composer, Artisan, cron jobs
phpX.Y-mysql	pdo_mysql, mysqli	MySQL/MariaDB apps, WordPress
phpX.Y-pgsql	pdo_pgsql	PostgreSQL apps
phpX.Y-mbstring	Multibyte strings	Laravel, Symfony, WordPress
phpX.Y-xml	DOM, SimpleXML, XMLWriter	Most frameworks and Composer packages
phpX.Y-curl	HTTP client	API calls, Guzzle
phpX.Y-zip	Zip archives	Composer, file exports
phpX.Y-intl	Locale and number formatting	Laravel, Symfony, e-commerce
phpX.Y-gd or phpX.Y-imagick	Image processing	WordPress media, thumbnails
phpX.Y-redis	Redis client	Caches, queues, sessions

Extensions are installed per version. Installing php8.4-redis does nothing for PHP 8.2. Check what each version has loaded:

php8.4 -m
php8.2 -m | grep -i redis

Step 4: Confirm Both PHP-FPM Services Are Running

Each version gets its own systemd service and socket:

systemctl status php8.4-fpm php8.2-fpm --no-pager
ls /run/php/
# php8.2-fpm.sock  php8.4-fpm.sock  php-fpm.sock

Item	PHP 8.4	PHP 8.2
CLI binary	/usr/bin/php8.4	/usr/bin/php8.2
FPM service	php8.4-fpm	php8.2-fpm
FPM socket	/run/php/php8.4-fpm.sock	/run/php/php8.2-fpm.sock
CLI php.ini	/etc/php/8.4/cli/php.ini	/etc/php/8.2/cli/php.ini
FPM php.ini	/etc/php/8.4/fpm/php.ini	/etc/php/8.2/fpm/php.ini
FPM pool config	/etc/php/8.4/fpm/pool.d/www.conf	/etc/php/8.2/fpm/pool.d/www.conf
Extra .ini files	/etc/php/8.4/mods-available/	/etc/php/8.2/mods-available/

Note that the CLI and FPM have separate php.ini files. If you raise memory_limit in the CLI file, your website won't see the change, and changing the FPM file won't affect Artisan or cron. To find the files a binary actually loads, run php8.4 --ini.

The version-less php-fpm.sock is a symlink managed by the alternatives system. It points to one version's socket. It's handy, but it's safer to use the explicit versioned socket in Nginx so that installing a new version never silently moves a site.

Step 5: Switch the Default PHP CLI Version with update-alternatives

The php command is a symlink chain managed by update-alternatives. Run the interactive picker:

sudo update-alternatives --config php

Or set the version directly, which is handy in scripts:

sudo update-alternatives --set php /usr/bin/php8.4
php -v

If you build PECL extensions, switch the related tools too so they match:

sudo update-alternatives --set phar /usr/bin/phar8.4
sudo update-alternatives --set phar.phar /usr/bin/phar.phar8.4
sudo update-alternatives --set phpize /usr/bin/phpize8.4
sudo update-alternatives --set php-config /usr/bin/php-config8.4

(The phpize and php-config alternatives only exist if you've installed php8.4-dev.)

You don't have to change the default at all. You can call a version directly by name, which is often clearer in cron jobs and deploy scripts:

php8.2 /var/www/legacy/artisan schedule:run
php8.4 /usr/local/bin/composer install --no-dev

update-alternatives only changes the command line. It doesn't affect which PHP your websites use. Nginx decides that in the next step.

Step 6: Point Each Nginx Site at Its Own PHP Version

The version a site runs depends on the socket in its fastcgi_pass line. Here are two sites on the same server running different versions:

# /etc/nginx/sites-available/new-app.conf
server {
    listen 80;
    server_name new.example.com;
    root /var/www/new-app/public;
    index index.php index.html;

    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/run/php/php8.4-fpm.sock;
    }
}

# /etc/nginx/sites-available/legacy-app.conf
server {
    listen 80;
    server_name legacy.example.com;
    root /var/www/legacy-app/public;
    index index.php index.html;

    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/run/php/php8.2-fpm.sock;
    }
}

Enable the sites, test, and reload:

sudo ln -s /etc/nginx/sites-available/new-app.conf /etc/nginx/sites-enabled/
sudo ln -s /etc/nginx/sites-available/legacy-app.conf /etc/nginx/sites-enabled/
sudo nginx -t && sudo systemctl reload nginx

To confirm which version a site really runs, temporarily drop a file into its web root, load it in a browser, and then delete it:

echo '<?php echo PHP_VERSION;' | sudo tee /var/www/legacy-app/public/version.php
curl -s http://legacy.example.com/version.php   # 8.2.x
sudo rm /var/www/legacy-app/public/version.php

The full FastCGI setup, socket permissions, and pm.max_children sizing are covered in how to configure PHP-FPM with Nginx.

Optional: A Separate PHP-FPM Pool per Site

By default, every site using PHP 8.4 shares the www pool and runs as www-data. If you want one site's PHP code isolated from another's, create a dedicated pool with its own user and socket:

; /etc/php/8.4/fpm/pool.d/new-app.conf
[new-app]
user = newapp
group = newapp
listen = /run/php/php8.4-fpm-new-app.sock
listen.owner = www-data
listen.group = www-data
pm = dynamic
pm.max_children = 10
pm.start_servers = 2
pm.min_spare_servers = 1
pm.max_spare_servers = 3

sudo useradd --system --no-create-home --shell /usr/sbin/nologin newapp
sudo php-fpm8.4 -t && sudo systemctl reload php8.4-fpm

Then use fastcgi_pass unix:/run/php/php8.4-fpm-new-app.sock; in that site's server block, and give newapp ownership of the directories the app writes to.

Step 7: Install Composer for a Local Development Environment

Composer runs on whichever PHP you call it with. Install it once, using the official installer from getcomposer.org/download, which also shows the current hash to verify against:

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
# compare the file's hash with the one published on getcomposer.org/download
php composer-setup.php --install-dir=/usr/local/bin --filename=composer
php -r "unlink('composer-setup.php');"
composer --version

To install a project's dependencies with a specific PHP version, call Composer through that binary: php8.2 /usr/local/bin/composer install. To stop Composer from resolving packages that only work on your laptop's newer PHP, pin the production version in the project's composer.json:

composer config platform.php 8.2.0

For quick local testing without Nginx, PHP's built-in server is enough:

cd ~/projects/my-app/public
php8.4 -S 127.0.0.1:8000

The built-in server is for development only. In production, put PHP-FPM behind Nginx.

Step 8: Upgrade a Site to a New PHP Version (and Remove the Old One)

Moving a site from PHP 8.2 to 8.4 is just a switch of sockets. You can roll it back by changing one line:

1. Install the same extensions for the new version (compare php8.2 -m with php8.4 -m).
2. Copy over only the settings you changed in /etc/php/8.2/fpm/php.ini and the pool file. Don't copy the whole files, because defaults differ between versions.
3. Run your test suite and composer install with php8.4.
4. Change fastcgi_pass to php8.4-fpm.sock, then run sudo nginx -t && sudo systemctl reload nginx.
5. Update cron jobs, queue workers, and deploy scripts that call php8.2 by name.
6. Watch the error log, /var/log/nginx/error.log, and your app logs for deprecation warnings and fatal errors.

When nothing uses the old version anymore, stop it and remove it:

sudo systemctl disable --now php8.2-fpm
sudo apt purge 'php8.2*'
sudo apt autoremove

Each idle PHP-FPM service keeps its own worker processes in memory, so don't leave versions running that no site uses.

Troubleshooting Multiple PHP Versions on Ubuntu

Symptom	Cause	Fix
Unable to locate package php8.4-fpm	PPA not added, or apt update not run after adding it	sudo add-apt-repository ppa:ondrej/php && sudo apt update
Apache installed itself and took port 80	Installed the php8.4 metapackage instead of php8.4-fpm	sudo apt purge apache2 libapache2-mod-php*, then install php8.4-fpm
php -v shows the wrong version	CLI alternative still points to the old binary	sudo update-alternatives --config php
Site still runs the old version after switching the CLI	Nginx uses fastcgi_pass, not the CLI	Change the socket in the server block, then reload Nginx
502 Bad Gateway, connect() to unix:/run/php/php8.4-fpm.sock failed (2: No such file or directory)	That FPM service isn't installed or running	sudo systemctl start php8.4-fpm; check ls /run/php/
Call to undefined function mysqli_connect() or could not find driver	Extension installed for a different version	Install phpX.Y-mysql for the version the site uses, then restart its FPM
php.ini change has no effect	Edited the CLI file instead of the FPM file (or the reverse)	Check the file against php8.4 --ini, edit the right one, sudo systemctl restart php8.4-fpm
Composer: Your requirements could not be resolved (PHP version)	Composer ran with a different PHP than the project targets	Run php8.2 /usr/local/bin/composer install or set config.platform.php

For more on gateway errors, see how to fix 502 Bad Gateway in Nginx.

Monitor Every Site After a PHP Upgrade

A PHP version switch is one of the easiest ways to break a site without noticing. The homepage loads fine, but a checkout page or an admin route hits a removed function and returns a 500. Testing each site by hand right after the switch helps. It doesn't help when something breaks at 3 a.m. after an unattended apt upgrade.

GreenCrew checks your sites over HTTP from outside your server and alerts you on Discord, Slack, or Telegram the moment one goes down. It also gives you a public status page to share with users. Add a check for each site, not just one per server, and point the checks at a page that actually runs PHP and touches the database, so a broken FPM pool counts as downtime. The setup is in how to get website downtime alerts on Discord, Slack, and Telegram.

Frequently Asked Questions

Can I run two PHP versions on the same server?

Yes. Packages from the ondrej/php PPA install into separate /etc/php/<version>/ directories, with separate binaries (php8.2, php8.4), FPM services, and sockets. Nginx picks the version for each site through fastcgi_pass, so one server can host sites on different versions at the same time.

Is the ondrej/php PPA safe to use in production?

It's the most widely used source of alternative PHP builds for Ubuntu, and its maintainer also packages PHP for Debian. It's still a third-party repository, though, so updates come from it rather than from Canonical. Pin the versioned package names you rely on, and test upgrades on staging first.

How do I install PHP 7.4 on Ubuntu?

The PPA has historically carried older branches like php7.4-fpm, and the install commands are the same as above. However, PHP 7.4 has been end of life since November 2022 and gets no security patches. Use it only to keep a legacy app running while you migrate it to a supported version, and plan that migration now.

Does update-alternatives change the PHP version Nginx uses?

No. update-alternatives --config php only changes which binary the php command runs: your shell, Composer, and cron jobs that call php. Nginx sends requests to whichever PHP-FPM socket is in each server block's fastcgi_pass line.

Conclusion

To install the PHP version you need on Ubuntu, add ppa:ondrej/php, install the versioned -fpm and -cli packages plus extensions for each version, and keep them in their own /etc/php/<version>/ directories. Use update-alternatives to choose the default CLI and fastcgi_pass to choose each site's version, so upgrades become a one-line, reversible change. If you're setting up the full stack, continue with how to install a LEMP stack on Ubuntu or how to deploy Laravel with Nginx. Then add GreenCrew checks so a PHP upgrade that breaks a site alerts you right away.