Upgrading Debian from version 12 (bookworm) to 13 (trixie) is an operation that should be performed in a repeatable and predictable way, especially on servers and containers (for example Proxmox LXC or virtual machines). Below you will find a simple guide and ready-to-use commands to download and run the upgrade script.

Before running the upgrade: create a backup or snapshot. In Proxmox, the best option is vzdump or a snapshot. On bare metal, at minimum back up /etc, applications, and databases.

• Proxmox LXC / VM: backup using vzdump or create a snapshot.
• Server: backup /etc, /var/www, databases (MySQL/PostgreSQL), and SSL certificates.

Script download:

https://soban.pl/bash/upgrade_to_debian13.sh

1) Backup before upgrade (examples)

Example backup in Proxmox (run on Proxmox host, replace CTID/VMID):

vzdump 101 --mode snapshot --compress zstd --storage local

Example simple filesystem backup on a server (this does not replace a full snapshot, but it’s better than nothing):

tar czf /root/backup_before_upgrade.tar.gz /etc /var/www /root

2) Download the script (wget / curl)

The easiest way is to use wget. If the wget command does not work even though the package is installed, use the full path /usr/bin/wget.

Variant A (standard wget):

apt update
apt install -y wget
cd /root
wget -O upgrade_to_debian13.sh https://soban.pl/bash/upgrade_to_debian13.sh
chmod +x upgrade_to_debian13.sh

Variant B (wget with full path – useful if PATH is broken):

apt update
apt install -y wget
cd /root
/usr/bin/wget -O upgrade_to_debian13.sh https://soban.pl/bash/upgrade_to_debian13.sh
chmod +x upgrade_to_debian13.sh

Variant C (curl):

apt update
apt install -y curl
cd /root
curl -fsSL -o upgrade_to_debian13.sh https://soban.pl/bash/upgrade_to_debian13.sh
chmod +x upgrade_to_debian13.sh

3) Script help (parameters)

Before running the upgrade, display available parameters and usage examples:

cd /root
./upgrade_to_debian13.sh --help

4) Upgrade Debian 12 → Debian 13 (system only)

If you are currently running Debian 12 (bookworm) and want to perform a system upgrade:

cd /root
./upgrade_to_debian13.sh

The script will create a backup of /etc/apt/sources.list, switch repositories to trixie, run apt update and apt full-upgrade, and finally execute autoremove and autoclean.

5) Auto-detect PHP/nginx and update if needed

If the container or VM is running a web stack and you want the script to automatically detect PHP usage (nginx + fastcgi_pass) and upgrade PHP and nginx if necessary:

cd /root
./upgrade_to_debian13.sh --auto

6) Force PHP and nginx upgrade (PHP-FPM socket fix)

If you want to force installation or upgrade of PHP and automatically fix nginx configuration to use the correct PHP-FPM socket:

cd /root
./upgrade_to_debian13.sh --with-php --with-nginx --php-version 8.2

This command installs PHP 8.2 (php-fpm and common modules) and replaces old PHP-FPM socket paths in nginx configuration with /run/php/php8.2-fpm.sock. Then it runs nginx -t and reloads or restarts services.

7) Already running Debian 13? PHP/nginx only mode

If the system is already running Debian 13 (trixie) and you only want to upgrade PHP and nginx without modifying system repositories:

cd /root
./upgrade_to_debian13.sh --php-nginx-only --with-php --with-nginx --php-version 8.2

8) Dry-run mode (test mode)

If you want to see what the script will do without making any changes:

cd /root
./upgrade_to_debian13.sh --auto --dry-run

9) Troubleshooting: wget installed but not working

If apt reports wget is installed but the shell shows command not found, it is usually a PATH issue. The easiest workaround is to use the full path: /usr/bin/wget.

echo "$PATH"
command -v wget || true
ls -l /usr/bin/wget || true
/usr/bin/wget --version || true

Summary

This solution provides a convenient way to upgrade Debian 12 → Debian 13 and optionally fix common PHP/nginx issues after upgrade (PHP-FPM socket paths, nginx config testing, and service restart). Always create a backup before upgrading and start by running --help to review available options.

Script: https://soban.pl/bash/upgrade_to_debian13.sh

Artykuł Automatic upgrade Debian 12 → Debian 13 with optional PHP and nginx update pochodzi z serwisu soban.