Potential Issues & Troubleshooting: Upgrading Qlik Sense Environment from Windows Server 2016 to 2025

[hyeongukKangSG]

Hello Qlik Community,

I am planning an OS migration for a Qlik Sense Enterprise environment from Windows Server 2016 to Windows Server 2025. Given the significant gap between these OS versions, I am concerned about potential service disruptions and technical conflicts.

I would like to ask for expert insights on anticipated issues and their solutions regarding the following areas:

1. Security & Cipher Suites (TLS 1.3):

• Windows 2025 supports TLS 1.3 by default. Has anyone encountered handshake issues between the Proxy Service and older clients or external load balancers?

• Potential Issue: Connectivity drops if the cipher suites aren't aligned.

• Question: Should I manually enforce TLS 1.2, or does Qlik Sense (Latest Release) handle TLS 1.3 natively without issues?

2. .NET Framework & Dependency Conflicts:

• Windows 2016 and 2025 have different native .NET versions.

• Potential Issue: Certain Qlik services or custom extensions might fail to initialize due to missing or mismatched .NET runtimes.

• Question: Are there specific .NET or C++ Redistributable versions that must be manually verified after the OS upgrade?

3. Repository Database (PostgreSQL) Stability:

• I am worried about the impact on the bundled PostgreSQL during the OS transition.

• Potential Issue: Database service failing to start due to changed file permissions or OS-level security hardening in Win 2025.

• Question: Is it safer to perform a standalone PostgreSQL backup/restore rather than relying on the Qlik installer's migration logic?

4. Kerberos & SPN Configuration:

• Potential Issue: Changes in Active Directory communication protocols or SMB signing in Windows 2025 might break existing Kerberos SSO.

• Question: Do I need to re-register SPNs or update delegation settings in AD after moving to the 2025 environment?

5. Performance & Resource Allocation:

• Windows 2025 has different memory management and indexing behaviors.

• Potential Issue: Unexpected high RAM usage or disk I/O bottlenecks during app reloads.

• Question: Are there any recommended OS-level optimizations (e.g., disabling specific Windows services) for Qlik on Win 2025?

Current Environment:

• Qlik Sense Version: November 2025

• Architecture: Multi-node (1 Central, 2 Rim nodes)

• Migration Strategy: Considering a clean install on Win 2025 followed by a site restore.

I would appreciate any "lessons learned" or "gotchas" from those who have pioneered this upgrade path.

Thank you!

[Eduardo_Monteiro · Accepted solution]

Hello @hyeongukKangSG 

---

**1. Should I manually enforce TLS 1.2, or does Qlik Sense handle TLS 1.3 natively?**

Do **not** enforce TLS 1.3 system-wide — it will break the Proxy Service. Enabling TLS 1.3 causes errors in Qlik Sense. The supported workaround is placing Qlik Sense behind a reverse proxy, using TLS 1.2 for internal Qlik service communications while the reverse proxy handles TLS 1.3 toward the browser. [Qlik Community](https://community.qlik.com/t5/Deployment-Management/TLS-1-3-Qliksense/td-p/2470980) The exception is the License Service: on Windows Server 2022 or higher, TLS 1.3 is automatically used by the Qlik License Service when available, and those cipher suites cannot be adjusted through configuration. [Qlik Help](https://help.qlik.com/en-US/sense-admin/May2024/Subsystems/DeployAdministerQSE/Content/Sense_DeployA...)

---

**2. Are there specific .NET or C++ Redistributable versions that must be manually verified after the OS upgrade?**

Since you're doing a clean install, the Qlik installer will lay down the correct dependencies. Focus your verification on custom extensions and ODBC/OLEDB connectors — these may have been compiled against older .NET targets and may need vendor updates or recompilation. Check that the Visual C++ Redistributable (x64) bundled with the November 2025 installer is present post-install via Programs & Features, and test each data connection individually before cutover.

---

**3. Is it safer to perform a standalone PostgreSQL backup/restore rather than relying on the Qlik installer's migration logic?**

Yes, absolutely. A complete backup of the Qlik Sense site and Repository Database should be taken before any major infrastructure change [Qlik Community](https://community.qlik.com/t5/Official-Support-Articles/Qlik-Sense-Enterprise-on-Windows-How-To-Upgr...) , using pg_dump/pg_restore — not the installer's migration logic. Also note: the version of Qlik Sense installed on the new server must exactly match the version from which the backup was taken. [Qlik Community](https://community.qlik.com/t5/Support-Updates/Qlik-Sense-Migration-Migrating-your-Entire-Qlik-Sense/...)

---

**4. Do you need to re-register SPNs or update delegation settings in AD after moving to the 2025 environment?**

Yes. An SPN must be set for both the short hostname and FQDN of the Qlik Sense server for Kerberos to work correctly. [Qlik Community](https://community.qlik.com/t5/Official-Support-Articles/Kerberos-authentication-with-Qlik-Sense/ta-p...) If your new servers have different machine names, existing SPNs will be stale and SSO will fail. Re-register SPNs for both short name and FQDN on the new servers, and update any constrained delegation settings in AD to reference the new server names.

---

**5. Are there recommended OS-level optimizations for Qlik on Windows Server 2025?**

Yes — Disable Windows Search indexing on all Qlik data volumes, add AV exclusions for `%ProgramData%\Qlik`, `%ProgramFiles%\Qlik`, and your UNC share path (real-time scanning of `.qvf`/`.qvd` files during reloads causes severe I/O bottlenecks), and set the Power Plan to High Performance.

Regards,