{"id":5441,"date":"2025-08-09T16:37:11","date_gmt":"2025-08-09T20:37:11","guid":{"rendered":"https:\/\/underhost.com\/blog\/?p=5441"},"modified":"2026-10-23T08:27:13","modified_gmt":"2026-10-23T12:27:13","slug":"debian-13-trixie-upgrade-guide-maximize-performance-on-underhost","status":"publish","type":"post","link":"https:\/\/underhost.com\/blog\/debian-13-trixie-upgrade-guide-maximize-performance-on-underhost\/","title":{"rendered":"Debian 13 &#8220;Trixie&#8221; Upgrade Guide: Move From Debian 12 Safely"},"content":{"rendered":"<div class=\"uh-blog-hero\" style=\"margin:0 0 40px;text-align:center;padding:48px 24px;border-radius:20px;background:linear-gradient(135deg,#0D1F3C 0%,#125A8A 58%,#176EA5 100%);color:#ffffff;box-shadow:0 20px 40px -15px rgba(13,31,60,0.28);position:relative;overflow:hidden;\">\n<div style=\"display:inline-flex;align-items:center;gap:8px;padding:7px 14px;margin-bottom:16px;border:1px solid rgba(0,212,255,0.32);border-radius:999px;color:#DFF8FF;font-size:12px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;background:rgba(0,212,255,0.10);\"><i class=\"fas fa-server\" style=\"color:#00D4FF;\"><\/i> Hosting Guide<\/div>\n<h1 style=\"color:#ffffff;font-size:clamp(32px,5vw,46px);line-height:1.12;margin:0 0 14px;font-weight:800;\">Debian 13 &#8220;Trixie&#8221; Upgrade Guide: Move From Debian 12 Safely<\/h1>\n<p style=\"font-size:18px;color:#EAF6FF;max-width:800px;margin:0 auto;line-height:1.7;\">Debian 13 delivers cutting-edge Linux performance\u2014learn how to upgrade from Debian 12 seamlessly and leverage UnderHost\u2019s NVMe VPS, offshore servers, and expert management for flawless deployment.<\/p>\n<\/div>\n<div class=\"uh-blog-excerpt\" style=\"border-left:4px solid #00D4FF;padding:18px 20px;margin:0 0 34px;background:#F8FAFC;color:#1F2937;border-radius:0 14px 14px 0;box-shadow:0 8px 28px rgba(13,31,60,0.08);line-height:1.75;\"><strong style=\"color:#0D1F3C;\">Short answer:<\/strong> Debian 13 &#8220;trixie&#8221; was released on 9 August 2025, with the Linux 6.12 LTS kernel, PHP 8.4, MariaDB 11.8, Python 3.13 and OpenSSH 10.0. To upgrade a Debian 12 server: back up, bring Debian 12 fully up to date, change the package sources from <code>bookworm<\/code> to <code>trixie<\/code>, then run <code>apt update<\/code>, <code>apt upgrade --without-new-pkgs<\/code> and <code>apt full-upgrade<\/code>, and reboot. Test the upgrade on a copy of the server first, because PHP and database versions change.<\/div>\n<nav class=\"uh-toc\" aria-label=\"Table of contents\" style=\"background:#ffffff;border:1px solid #E5E7EB;border-radius:16px;padding:20px 22px;margin:0 0 34px;box-shadow:0 4px 12px rgba(13,31,60,0.08);\">\n<div style=\"font-size:12px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;color:#176EA5;margin-bottom:10px;\"><i class=\"fas fa-list\" style=\"color:#00D4FF;\"><\/i> In this guide<\/div>\n<ol style=\"margin:0;padding-left:20px;columns:2 260px;column-gap:28px;line-height:1.9;\">\n<li><a href=\"#what-is-new-in-debian-13\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">What is new in Debian 13<\/a><\/li>\n<li><a href=\"#what-can-break-on-a-web-server\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">What can break on a web server<\/a><\/li>\n<li><a href=\"#before-you-upgrade\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Before you upgrade<\/a><\/li>\n<li><a href=\"#step-1-bring-debian-12-up-to-date\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 1: bring Debian 12 up to date<\/a><\/li>\n<li><a href=\"#step-2-point-the-package-sources-at-trixie\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 2: point the package sources at trixie<\/a><\/li>\n<li><a href=\"#step-3-run-the-upgrade\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 3: run the upgrade<\/a><\/li>\n<li><a href=\"#step-4-reboot-and-check\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 4: reboot and check<\/a><\/li>\n<li><a href=\"#step-5-clean-up\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 5: clean up<\/a><\/li>\n<li><a href=\"#upgrade-or-start-fresh\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Upgrade or start fresh?<\/a><\/li>\n<li><a href=\"#troubleshooting\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Troubleshooting<\/a><\/li>\n<li><a href=\"#check-the-upgrade-on-a-test-server-first\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Check the upgrade on a test server first<\/a><\/li>\n<li><a href=\"#notes-on-php-and-databases-after-the-upgrade\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Notes on PHP and databases after the upgrade<\/a><\/li>\n<li><a href=\"#plan-a-rollback-before-you-start\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Plan a rollback before you start<\/a><\/li>\n<\/ol>\n<\/nav>\n<div class=\"uh-post-content\" style=\"color:#1F2937;font-size:16px;line-height:1.75;\">\n<h2 id=\"what-is-new-in-debian-13\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-info-circle\" style=\"color:#00D4FF;\"><\/i> What is new in Debian 13<\/h2>\n<div style=\"overflow-x:auto;margin:26px 0;border:1px solid #E5E7EB;border-radius:14px;-webkit-overflow-scrolling:touch;\">\n<table style=\"width:100%;border-collapse:collapse;background:#ffffff;color:#1F2937;font-size:15px;line-height:1.55;margin:0;min-width:600px;\">\n<thead>\n<tr style=\"background:#0D1F3C;color:#fff;\">\n<th style=\"padding:14px;text-align:left;\">Component<\/th>\n<th style=\"padding:14px;text-align:left;\">Debian 12 (bookworm)<\/th>\n<th style=\"padding:14px;text-align:left;\">Debian 13 (trixie)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Linux kernel<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">6.1<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">6.12 LTS<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">PHP<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">8.2<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">8.4<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">MariaDB<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">10.11<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">11.8<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">PostgreSQL<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">15<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">17<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Python 3<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">3.11<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">3.13<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">GCC<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">12.2<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">14.2<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">OpenSSH<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">9.2<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">10.0<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">OpenSSL<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">3.0<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">3.5<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">systemd<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">252<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">257<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Nginx<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">1.22<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">1.26<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p style=\"margin:0 0 18px;\">Debian 13 also adds official support for the riscv64 architecture, and it is the last release for armel. The 32-bit i386 architecture is no longer a regular install target: there is no i386 kernel or installer, so a 32-bit server should not be upgraded. Debian says trixie will be supported for five years through the Security and Long Term Support teams.<\/p>\n<h2 id=\"what-can-break-on-a-web-server\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-server\" style=\"color:#00D4FF;\"><\/i> What can break on a web server<\/h2>\n<ul style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\"><strong>PHP 8.4.<\/strong> Old plugins, themes and custom code may not support it. Check your applications before you upgrade.<\/li>\n<li style=\"margin:0 0 8px;\"><strong>MariaDB 11.8.<\/strong> The database files are upgraded on first start. Take a full SQL dump first, because you cannot go back without it.<\/li>\n<li style=\"margin:0 0 8px;\"><strong>OpenSSH 10.0.<\/strong> DSA keys are no longer supported. If you still log in with a DSA key, create an Ed25519 key before the upgrade.<\/li>\n<li style=\"margin:0 0 8px;\"><strong>Changed configuration files.<\/strong> If you edited files in <code>\/etc<\/code>, apt asks whether to keep your version or take the new one.<\/li>\n<li style=\"margin:0 0 8px;\"><strong>Third-party repositories.<\/strong> Sources such as PHP or Node.js repositories may not have trixie packages yet. Disable them for the upgrade.<\/li>\n<\/ul>\n<h2 id=\"before-you-upgrade\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-clipboard-check\" style=\"color:#00D4FF;\"><\/i> Before you upgrade<\/h2>\n<ul style=\"list-style:none;padding-left:0;\">\n<li style=\"margin:0 0 8px;\">\u2713 Take a full backup or a snapshot of the server, and a separate SQL dump of every database.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Make sure you can reach the server console (VNC or KVM) in case SSH does not come back after the reboot.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Check the version with <code>cat \/etc\/debian_version<\/code>. Only upgrades from Debian 12 are supported.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Check for held packages with <code>apt-mark showhold<\/code> and package problems with <code>dpkg --audit<\/code>.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Have at least 5 GB of free disk space. Check with <code>df -h<\/code>.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Plan a maintenance window. Websites go down while services restart.<\/li>\n<\/ul>\n<h2 id=\"step-1-bring-debian-12-up-to-date\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 1: bring Debian 12 up to date<\/h2>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>apt update\napt full-upgrade -y\napt autoremove --purge\nreboot<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">Reboot if a new kernel was installed, then log in again. Run the rest of the upgrade inside <code>screen<\/code> or <code>tmux<\/code>, so a dropped SSH connection does not stop it:<\/p>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>apt install -y screen\nscreen -S upgrade<\/code><\/pre>\n<h2 id=\"step-2-point-the-package-sources-at-trixie\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 2: point the package sources at trixie<\/h2>\n<p style=\"margin:0 0 18px;\">Remove or disable any third-party repositories first. Then change the Debian sources:<\/p>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code># Classic format\nsed -i \"s\/bookworm\/trixie\/g\" \/etc\/apt\/sources.list\n\n# If you use .sources files (deb822 format)\nsed -i \"s\/bookworm\/trixie\/g\" \/etc\/apt\/sources.list.d\/*.sources\n\n# Check the result\ngrep -r \"trixie\" \/etc\/apt\/sources.list \/etc\/apt\/sources.list.d\/<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">Debian 13 recommends the newer deb822 format, in <code>\/etc\/apt\/sources.list.d\/debian.sources<\/code>. Your old file still works, and you can convert it after the upgrade.<\/p>\n<h2 id=\"step-3-run-the-upgrade\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 3: run the upgrade<\/h2>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>apt update\n\n# Check the disk space needed\napt -o APT::Get::Trivial-Only=true full-upgrade\n\n# Minimal upgrade first, then the full upgrade\napt upgrade --without-new-pkgs\napt full-upgrade<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">Read each question apt asks about configuration files. If you changed a file, keeping your version is usually safest. Compare it with the new version afterwards.<\/p>\n<h2 id=\"step-4-reboot-and-check\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 4: reboot and check<\/h2>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>reboot\n\n# After logging back in\ncat \/etc\/debian_version          # should show 13.x\nuname -r                         # should show a 6.12 kernel\nsystemctl --failed               # list services that did not start\nphp -v &amp;&amp; mysql -V               # check PHP and MariaDB<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">Open your websites, test logins and forms, and check that cron jobs and email still work.<\/p>\n<h2 id=\"step-5-clean-up\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 5: clean up<\/h2>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>apt autoremove --purge\napt list \"?obsolete\"             # packages no longer in Debian 13\napt purge \"?obsolete\"            # remove them after checking the list<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">Re-enable third-party repositories only when they offer trixie packages.<\/p>\n<h2 id=\"upgrade-or-start-fresh\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-angle-double-right\" style=\"color:#00D4FF;\"><\/i> Upgrade or start fresh?<\/h2>\n<p style=\"margin:0 0 18px;\">An in-place upgrade keeps your server and IP address, and works well for simple servers. For servers that have collected years of changes, a fresh Debian 13 server is often cleaner: install it, move the sites and databases, test, then switch DNS. On a Cloud VPS you can build the new server next to the old one and keep the old one until the move is done. See our guide to <a href=\"https:\/\/underhost.com\/blog\/how-to-migrate-your-website-to-underhost-without-downtime\/\">moving a website without downtime<\/a>.<\/p>\n<h2 id=\"troubleshooting\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-exclamation-triangle\" style=\"color:#00D4FF;\"><\/i> Troubleshooting<\/h2>\n<div style=\"overflow-x:auto;margin:26px 0;border:1px solid #E5E7EB;border-radius:14px;-webkit-overflow-scrolling:touch;\">\n<table style=\"width:100%;border-collapse:collapse;background:#ffffff;color:#1F2937;font-size:15px;line-height:1.55;margin:0;\">\n<thead>\n<tr style=\"background:#0D1F3C;color:#fff;\">\n<th style=\"padding:14px;text-align:left;\">Problem<\/th>\n<th style=\"padding:14px;text-align:left;\">Fix<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">apt reports broken or held packages<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Run <code>apt --fix-broken install<\/code>, then <code>apt full-upgrade<\/code> again.<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">PHP-FPM does not start<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Debian 13 uses the php8.4-fpm service. Install it, move your pool settings, and update the web server configuration.<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">MariaDB does not start<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Read <code>journalctl -u mariadb<\/code>. Restore from your SQL dump if the data cannot be upgraded.<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">The server does not boot<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Use the console and pick the previous kernel in the GRUB menu, then check the logs.<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">SSH login fails<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Use the console. Check for DSA keys and run <code>sshd -t<\/code> to test the configuration.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div aria-hidden=\"true\" class=\"uh-section-divider\" style=\"width:min(100% - 32px, 1080px);margin:44px auto;display:grid;grid-template-columns:1fr 32px 1fr;align-items:center;gap:18px;pointer-events:none;\"><span style=\"height:1px;background:linear-gradient(90deg,transparent,rgba(0,212,255,0.40),rgba(23,110,165,0.24),transparent);\"><\/span><img alt=\"\" decoding=\"async\" height=\"32\" loading=\"lazy\" src=\"https:\/\/cdn.underhost.com\/android-chrome-192x192.webp\" style=\"width:32px;height:32px;display:block;border-radius:8px;filter:drop-shadow(0 0 14px rgba(0,212,255,0.30));\" width=\"32\"\/><span style=\"height:1px;background:linear-gradient(90deg,transparent,rgba(23,110,165,0.24),rgba(0,212,255,0.40),transparent);\"><\/span><\/div>\n<h2 id=\"check-the-upgrade-on-a-test-server-first\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-clipboard-check\" style=\"color:#00D4FF;\"><\/i> Check the upgrade on a test server first<\/h2>\n<p style=\"margin:0 0 18px;\">Before you upgrade a live server, build the same setup on a spare machine or a snapshot, run the upgrade there, and test your applications. This shows which packages, configuration files or plugins need attention without risking the live sites.<\/p>\n<h2 id=\"notes-on-php-and-databases-after-the-upgrade\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-database\" style=\"color:#00D4FF;\"><\/i> Notes on PHP and databases after the upgrade<\/h2>\n<ul style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\">Check that each application supports the PHP version Debian 13 provides before you move production sites to it.<\/li>\n<li style=\"margin:0 0 8px;\">Check your database&#8217;s release notes for changed defaults, and take a dump before the upgrade.<\/li>\n<li style=\"margin:0 0 8px;\">Restart each service after the upgrade, and check its log for warnings.<\/li>\n<\/ul>\n<h2 id=\"plan-a-rollback-before-you-start\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-clipboard-check\" style=\"color:#00D4FF;\"><\/i> Plan a rollback before you start<\/h2>\n<p style=\"margin:0 0 18px;\">Decide now how you would go back if the upgrade fails. Keep the snapshot until the site has run normally for several days, and write down the commands that restore each service so they are ready during an outage.<\/p>\n<ul style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\">Keep the pre-upgrade backup and the SQL dump until the upgrade is confirmed.<\/li>\n<li style=\"margin:0 0 8px;\">Know how to reach the server console if SSH stops responding after the reboot.<\/li>\n<\/ul>\n<div aria-hidden=\"true\" class=\"uh-section-divider\" style=\"width:min(100% - 32px, 1080px);margin:44px auto;display:grid;grid-template-columns:1fr 32px 1fr;align-items:center;gap:18px;pointer-events:none;\"><span style=\"height:1px;background:linear-gradient(90deg,transparent,rgba(0,212,255,0.40),rgba(23,110,165,0.24),transparent);\"><\/span><img alt=\"\" decoding=\"async\" height=\"32\" loading=\"lazy\" src=\"https:\/\/cdn.underhost.com\/android-chrome-192x192.webp\" style=\"width:32px;height:32px;display:block;border-radius:8px;filter:drop-shadow(0 0 14px rgba(0,212,255,0.30));\" width=\"32\"\/><span style=\"height:1px;background:linear-gradient(90deg,transparent,rgba(23,110,165,0.24),rgba(0,212,255,0.40),transparent);\"><\/span><\/div>\n<\/div>\n<div class=\"uh-blog-cta\" style=\"background:linear-gradient(135deg,#0D1F3C 0%,#125A8A 58%,#176EA5 100%);color:#ffffff;padding:36px 24px;border-radius:20px;text-align:center;margin:44px 0;box-shadow:0 20px 40px -15px rgba(13,31,60,0.32);\">\n<h2 style=\"margin:0 0 12px;font-size:28px;line-height:1.25;color:#ffffff;\">Need help with this?<\/h2>\n<p style=\"font-size:17px;margin:0 auto 22px;color:#EAF6FF;max-width:720px;line-height:1.7;\">Prefer to have the upgrade done for you? Our server management team can test, upgrade and check your Debian server.<\/p>\n<p><a href=\"https:\/\/underhost.com\/server-management.php\" style=\"background:linear-gradient(90deg,#00D4FF,#0077FF);color:#ffffff;padding:13px 28px;border-radius:10px;text-decoration:none;font-weight:800;display:inline-block;margin:8px;\">See server management plans<\/a><a href=\"https:\/\/customerpanel.ca\/client\/\" style=\"background:transparent;color:#ffffff;padding:12px 28px;border-radius:10px;text-decoration:none;font-weight:800;display:inline-block;margin:8px;border:1px solid rgba(255,255,255,0.32);\">Contact @CustomerPanel<\/a><\/div>\n<div class=\"uh-faq-section\" id=\"faq\" style=\"margin:34px 0;scroll-margin-top:90px;\">\n<h2 style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:0 0 18px;border-bottom:2px solid rgba(0,212,255,0.22);padding-bottom:10px;\">Frequently asked questions<\/h2>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">When was Debian 13 released?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Debian 13 &#8220;trixie&#8221; was released on 9 August 2025.<\/p>\n<\/div>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">Can I upgrade straight from Debian 11 to Debian 13?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">No. Only upgrades from Debian 12 are supported. Upgrade to Debian 12 first, or build a fresh Debian 13 server.<\/p>\n<\/div>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">Will my websites keep working after the upgrade?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Usually, but Debian 13 ships PHP 8.4 and MariaDB 11.8. Check that your applications support them, and test on a copy of the server first.<\/p>\n<\/div>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">How long will Debian 13 be supported?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Debian says trixie will be supported for five years, through regular security support followed by Long Term Support.<\/p>\n<\/div>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">Can I install Debian 13 on an UnderHost Cloud VPS?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Yes. Debian is one of the operating systems you can choose when you order a Cloud VPS. See the Cloud VPS page for the current list.<\/p>\n<\/div>\n<\/div>\n<p><!-- uh-related-start --><\/p>\n<div style=\"background:#F4F8FC;border:1px solid #DCE7F3;border-radius:14px;padding:18px 22px;margin:32px 0 8px;\">\n<h2 style=\"margin:0 0 12px;font-size:22px;\">Related guides<\/h2>\n<ul style=\"margin:0;padding-left:20px;\">\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/install-ffmpeg-on-linux\/\">Install FFmpeg on AlmaLinux, Debian, CentOS, and Ubuntu (Updated Guide)<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/how-to-install-cloudpanel-on-ubuntu-and-debian-servers\/\">How to Install CloudPanel on Ubuntu and Debian Servers<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/top-5-signs-its-time-to-upgrade-to-a-dedicated-server\/\">Top 5 Signs It&#8217;s Time to Upgrade to a Dedicated Server<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/underhosts-next-generation-server-upgrade\/\">UnderHost&#8217;s Next-Generation Server Upgrade<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/how-to-upgrade-my-exim-mail-server-on-cpanel-servers\/\">How to Upgrade Your Exim Mail Server on cPanel Servers<\/a><\/li>\n<\/ul>\n<\/div>\n<p><!-- uh-related-end --><br \/>\n<script type=\"application\/ld+json\">{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"When was Debian 13 released?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Debian 13 \\\"trixie\\\" was released on 9 August 2025.\"}}, {\"@type\": \"Question\", \"name\": \"Can I upgrade straight from Debian 11 to Debian 13?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"No. Only upgrades from Debian 12 are supported. Upgrade to Debian 12 first, or build a fresh Debian 13 server.\"}}, {\"@type\": \"Question\", \"name\": \"Will my websites keep working after the upgrade?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Usually, but Debian 13 ships PHP 8.4 and MariaDB 11.8. Check that your applications support them, and test on a copy of the server first.\"}}, {\"@type\": \"Question\", \"name\": \"How long will Debian 13 be supported?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Debian says trixie will be supported for five years, through regular security support followed by Long Term Support.\"}}, {\"@type\": \"Question\", \"name\": \"Can I install Debian 13 on an UnderHost Cloud VPS?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. Debian is one of the operating systems you can choose when you order a Cloud VPS. See the Cloud VPS page for the current list.\"}}]}<\/script><\/p>\n<h2 id=\"sources\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-book\" style=\"color:#00D4FF;\"><\/i> Sources<\/h2>\n<ul style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/www.debian.org\/News\/2025\/20250809\">Debian 13 &#8220;trixie&#8221; release announcement<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/www.debian.org\/releases\/trixie\/release-notes\/whats-new.en.html\">Debian 13 release notes: what is new<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/www.debian.org\/releases\/trixie\/release-notes\/upgrading.en.html\">Debian 13 release notes: upgrading from Debian 12<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Debian 13 delivers cutting-edge Linux performance\u2014learn how to upgrade from Debian 12 seamlessly and leverage UnderHost\u2019s NVMe VPS, offshore servers, and expert management for flawless deployment.<\/p>\n","protected":false},"author":1,"featured_media":5436,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[81,25],"tags":[120,113,185],"class_list":["post-5441","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hosting-guides","category-linux","tag-tag-cloud-vps","tag-tag-debian","tag-php"],"_links":{"self":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts\/5441","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/comments?post=5441"}],"version-history":[{"count":10,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts\/5441\/revisions"}],"predecessor-version":[{"id":6757,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts\/5441\/revisions\/6757"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/media\/5436"}],"wp:attachment":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/media?parent=5441"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/categories?post=5441"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/tags?post=5441"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}