Upgrading the Operating System of a ConfigMgr Site Server – Backup/Restore Option

A few days ago, a ConfigMgr (SCCM) administrator reached out to me seeking a high-level overview of the process for upgrading the operating system of a ConfigMgr Site Server. Specifically, he was interested in understanding the key steps involved in performing the upgrade through a backup and restore approach.

Credits: I want to give a big thanks to Jason Sandys for his initial work on the topic. This post is based on Jason's backup and recovery guidelines but has been updated to current versions of ConfigMgr and my findings from years and years of ConfigMgr consulting work.

Upgrading the Operating System of a Site Server

ConfigMgr offers two options for upgrading the operating system of a site server: an in-place upgrade or a backup and restore. For the in-place upgrade option, Microsoft provides a good high-level overview at this link: Upgrade on-premises infrastructure that supports Configuration Manager. For a more detailed guide I recommend reading up on Paul Winstanley's guide from 2021: In-Place Upgrade of ConfigMgr site server from Windows 2012 R2 to 2019.

While I’ve encountered administrators who have successfully performed in-place upgrades of ConfigMgr site servers, I’ve also seen cases where things didn’t go as smoothly. In some instances, issues surface much later—sometimes even a year down the line—directly tied to the fact that the server was upgraded in-place. These delayed issues can be challenging and time-consuming to diagnose and resolve.

Personally, I recommend the backup and restore approach. This involves backing up the existing site server, setting up a clean, pristine server with the same computer name, and restoring the backup. While this method typically takes longer—usually 1–2 days, including verification—it provides a more reliable and maintainable solution in the long run, reducing the risk of lingering or unexpected issues.

SQL Server Preparation

While SQL Server does support restoring an older database version to a newer SQL Server version, you may want to upgrade SQL Server before the migration. I have taken the stance that it's safer to restore the same version I'm migrating from; otherwise, I may end up troubleshooting two issues on the target server. Was it the SQL Database Upgrade that failed, or the ConfigMgr restore process?

For example, if you are running Windows Server 2016 with SQL Server 2016 and plan to migrate to Windows Server 2022, you cannot move the database as-is. SQL Server 2016 is not supported on Windows Server 2022, so I recommend upgrading SQL Server to a supported version, such as SQL Server 2019 or SQL Server 2022, before moving the database to the new server.

Using the Backup and Restore Option – Key Steps

This guide outlines the recommended steps for upgrading the operating system of a ConfigMgr Site Server using the backup and restore option. For these steps to work, you need to be a local administrator on the site server and have SQL sysadmin privileges. These steps also assume that your SQL Server is local to the Site Server as it should be.

Warning: You better familiarize yourself with these steps in a lab first, multiple times, and document every step of the process. These steps may look easy, but there are many moving parts to a ConfigMgr environment. If you don't have a lab, check out this free training on Building the Perfect Lab for ConfigMgr, MDT, and Intune.

On the Old Site Server

1. Preparation. Perform a health check and document configurations, including account credentials, NTFS permissions, certificates, and content locations. For documentation, I recommend Paul Wetter's Configuration Manager Documentation Script.
2. Role Removal. If needed, meaning if you will be restoring the site to a system with an upgraded operating system, remove roles such as Software Update Point, Management Point, Distribution Point, and Reporting Services Point. These roles are usually not on the Site Server, but smaller environments may have them.
   
   Note #1: Removing the Distribution Point role is rarely required. but unless you have a minimal ConfigMgr environment, you want this role on one or more remote servers instead of on the site server.
   
   Note #2: Keep an eye on the sitecomp.log for successful removal (deinstallation) of the roles.
   
3. Disable ConfigMgr Services. Stop and disable all ConfigMgr services on the site server and any remote management points.
4. Backup absolutely everything! Backup SQL databases, site server file systems, custom reports, etc.
5. List Shares. Get a list of all shared folders and their permissions.
6. Disable SQL Server Services. Stop and disable all SQL Server services on the site server.
7. Rename Server. Rename the old server (e.g., to “oldCMserver”) to keep it online for reference.

On the New Site Server

• Server Setup. Build a new server with "somewhat" matching volumes, drive letters, and a newer supported OS version. Join it to the domain and assign the same computer name as the old server.
• Configure Permissions. Add the new Site Server computer object to the local Administrators group of all other Site System Servers. Also, add it to the System Management container in Active Directory.
• Install Pre-requisites. Install SQL Server, WSUS, the Windows ADK, and ConfigMgr prerequisites.
• Copy Data. Copy SCCMContentLib and cd.latest from the Old Site Server to the New Site Server. If Data sources were stored on the site server itself, copy them too, and share the folder.
• Restore ConfigMgr. Restore the SQL database, and complete the ConfigMgr installation using the Recovery option in the setup. Complete any post-recovery tasks listed.
• Roles. Re-add roles removed during preparation (or host them on a separate site system).
• Reports and Accounts. Re-import custom reports and account credentials.
• Backup absolutely everything! Backup SQL databases, site server file systems, custom reports, etc.
• Test, test, and test. Validate the installation and perform extensive testing

Site Server and SQL Upgrades

If you are planning on doing Site Server and/or SQL upgrades as part of the project, I recommend doing that before starting this process, but technically, you can do that later as well.