In-Place upgrade from SQL Server 2017 to SQL Server 2025

Question

In-Place upgrade from SQL Server 2017 to SQL Server 2025

Chaitanya Kiran 841

Hi All,

We are doing In-Place upgrade from SQL Server 2017 to SQL Server 2025. We have replication configured. What is the order we must follow?

Thanks,

Chaitanya

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Answer 1

Marcin Policht 94,940 MVP Volunteer Moderator

SQL Server 2025 introduces some breaking changes regarding upgraded encryption standards so it's important to incorporate some specific steps in the upgrade process to ensure your replication components do not fail post-upgrade.

Before upgrading, take full backups of your user databases and the master, msdb, and model system databases. Ensure the Distributor is running the same or a higher SQL Server version than the Publisher. If the Distributor is on a separate instance, upgrade it before upgrading the Publisher. Because SQL Server 2025 enforces enhanced encryption and TDS 8 defaults, confirm that all replication servers have valid, non-expired TLS/SSL certificates installed and tested prior to the upgrade.

Run the SQL Server 2025 installation media as Administrator. In the SQL Server Installation Center, select Installation, then choose Upgrade from a previous version of SQL Server. Follow the wizard, accept the license terms, and select the instance to upgrade. During the process, SQL Server services will restart automatically, causing temporary downtime for replicated databases.

After the upgrade, verify certificates and Service Principal Names (SPNs). SQL Server 2025 applies stricter encryption requirements, so you may also need to refresh SPNs and ensure your connection drivers, such as the Microsoft OLE DB Driver for SQL Server, are updated. If replication fails or stops synchronizing after the upgrade, generate a new snapshot and reinitialize the subscriber databases.

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin

Chaitanya Kiran 841 Reputation points

2026-06-26T11:52:54.6866667+00:00

Which one should we upgrade first? Publisher or Subscriber? Please mention the order.
Marcin Policht 94,940 Reputation points MVP Volunteer Moderator

2026-06-26T12:28:38.6866667+00:00

The order would be Distributor → Publisher → Subscriber

The Distributor should be running the same or a newer SQL Server version than the Publisher, so upgrade the Distributor first if it is hosted on a separate instance. After that, upgrade the Publisher, and finally upgrade the Subscriber(s).

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin
Erland Sommarskog 135.1K Reputation points MVP Volunteer Moderator

2026-06-26T21:43:07.3033333+00:00

A few clarifications to Marcin's post. It is not SQL Server per se that enforces the higher encryption standards, but it is the OLE DB Driver MSSQLOLEDB19, which has been out for a while. What is new in SQL 2025 is that SQL 2025 uses MSOLEDBSQL19 rather than MSSQLOLEDB like SQL 2022 did.

MSOLEDBSQL19, like all recent drivers from Microsoft, defaults to requiring an encrypted connection, and by default it requires a trusted server certificate. That is, a certificate that is in the Trust Certificates store, or a certificate of which the root certificate is trusted. Depending on how you have set up distributor and subscribers, connections may start failing.

If you are in the fortunate situations that all machines that are involved are virtual machines, I strongly recommend that clone all of them, and restore them in a lab environment to test the upgrade. If they are physical machines, you would have to set up a new environment from scratch, if you don't have a test environment.
Lakshmi Narayana Garikapati 1,335 Reputation points Microsoft External Staff Moderator

2026-07-01T05:45:00.4833333+00:00

Hi @Chaitanya Kiran ,

Following up to confirm if the earlier responses addressed your query. If not, please share your questions and we'll assist further

Thanks,

Lakshmi