Microsoft released SQL Server 2014 SP3 Cumulative Update 3 (CU3) and SP2 Cumulative Update 17 (CU17) in August 2021, delivering targeted bug fixes across performance, backup and restore, Always On availability groups, and Full-Text Search. If you're still running SQL Server 2014 in production, these updates are worth applying, and this article explains what's in them and how to approach the deployment safely.

SQL Server 2014 reached end of extended support in July 2024. That doesn't mean organisations running it are doing something wrong. Plenty of Australian businesses operate legacy systems tied to SQL Server 2014 for valid reasons, whether that's application compatibility, licensing constraints, or a migration project that's still in progress. But running an unsupported version without keeping cumulative updates current is where the real risk sits. These CUs represent the final meaningful patch releases for the 2014 branch, and if you haven't applied them yet, now is the time to understand what you're missing.

What Is Included in SQL Server 2014 SP3 CU3?

SQL Server 2014 SP3 CU3 (KB5005619) includes more than 10 bug fixes targeting stability and security across several functional areas. The fixes cover:

  • Performance issues - Corrections to query execution behaviour that could cause unexpected slowdowns under certain workloads
  • Database backup and restore - Fixes addressing edge cases in backup reliability, which is critical for any production environment
  • Security improvements - Patches addressing vulnerabilities identified since SP3 CU2
  • General engine stability - Fixes for crashes and assertion failures that could occur in specific scenarios

The build number for SP3 CU3 is 12.0.6439.10. If you're on SP3 and your current build is lower than this, you're missing these fixes.

To check your current SQL Server 2014 build, run this query:

SELECT @@VERSION AS SQLServerVersion,
       SERVERPROPERTY('ProductVersion') AS ProductVersion,
       SERVERPROPERTY('ProductLevel') AS ProductLevel,
       SERVERPROPERTY('Edition') AS Edition;

Compare the output against the SQL Server 2014 build versions list to confirm where you stand.

What Is Included in SQL Server 2014 SP2 CU17?

SQL Server 2014 SP2 CU17 (KB5005620) is a larger update, containing more than 15 bug fixes. The notable areas addressed include:

  • Always On availability groups - Fixes for issues that could affect failover reliability and secondary replica synchronisation
  • Full-Text Search - Corrections to indexing and query behaviour in Full-Text Search workloads
  • Query optimiser improvements - Changes to plan generation that can affect query performance, particularly for complex queries with multiple joins or subqueries
  • Windows and .NET Framework compatibility - Updates to ensure correct behaviour on current Windows Server versions and .NET Framework releases

The build number for SP2 CU17 is 12.0.5659.1.

It's worth noting that if you're on SP2, Microsoft's recommendation has long been to move to SP3 where possible. SP3 is the final service pack for SQL Server 2014 and contains all SP2 fixes plus additional improvements. That said, if your environment is locked to SP2 for any reason, CU17 gets you as current as you can be on that branch.

Should You Apply These Updates?

Yes, if you're running SQL Server 2014 in production, you should apply the appropriate cumulative update for your service pack level. The question isn't really whether to apply them, but how to do it safely.

The fixes in both CU3 and CU17 address real-world problems. The backup and restore fixes in SP3 CU3 alone justify the update for any environment where data integrity matters, which is every production environment. The Always On fixes in SP2 CU17 are equally important for organisations relying on availability groups for high availability.

Cumulative updates for SQL Server are cumulative by definition. Each CU includes all fixes from previous CUs in that service pack branch. So applying SP3 CU3 gives you everything from SP3 CU1 and CU2 as well.

How to Apply SQL Server 2014 Cumulative Updates Safely

Applying a cumulative update to a production SQL Server instance requires a structured approach. Rushing this process is one of the more common causes of avoidable downtime.

Step 1: Check your current version

Run the version query above and document your current build number before making any changes.

Step 2: Download the update

Download the CU directly from the Microsoft Support Knowledge Base article:

Step 3: Test in a non-production environment first

This isn't optional. Apply the update to a dev or test instance that mirrors your production configuration as closely as possible. Run your application's standard workload against it and check for any behavioural changes, particularly around query plans if you have plan guides or forced parameterisation in place.

Step 4: Take a full backup before patching production

Before touching production, take a full backup of all user databases and the system databases (master, msdb, model). Verify the backups are readable. A cumulative update that goes wrong mid-installation is uncommon but not impossible, and you want a clean restore point.

Step 5: Plan for a maintenance window

SQL Server CU installations require a service restart. For a standalone instance, this means downtime. For an Always On environment, you can rolling-patch secondary replicas first, then fail over and patch the former primary, minimising total downtime. Plan the window accordingly and communicate it to stakeholders.

Step 6: Apply and verify

Run the installer on the production instance during the maintenance window. After the service restarts, run the version query again to confirm the build number has updated correctly. Check the SQL Server error log for anything unexpected immediately after startup.

Step 7: Monitor post-patching

Watch query performance and error logs for 24 to 48 hours after applying the update. CUs occasionally change query plan behaviour, particularly when they include query optimiser fixes. If you see unexpected plan regressions, Query Store (if enabled) can help you identify and force previous plans while you investigate.

What About SQL Server 2014 End of Life?

SQL Server 2014 extended support ended on 9 July 2024. Microsoft no longer releases security patches for it unless you're enrolled in Extended Security Updates (ESU), which is available through Azure Arc. If you're running SQL Server 2014 without ESU coverage after that date, you're operating without security patch coverage, which is a genuine risk.

Applying SP3 CU3 or SP2 CU17 addresses vulnerabilities identified before the end of support, but it doesn't change the fundamental exposure of running an end-of-life product. If SQL Server 2014 is still in your environment, a migration plan to SQL Server 2019 or SQL Server 2022 should be on the roadmap. Both versions offer significant performance, security, and feature improvements, and the upgrade path from 2014 is well-documented.

Key Takeaways

  • SQL Server 2014 SP3 CU3 (build 12.0.6439.10) and SP2 CU17 (build 12.0.5659.1) deliver important bug fixes covering backup and restore reliability, Always On availability groups, Full-Text Search, and query optimiser behaviour.
  • Always test cumulative updates in a non-production environment before applying to production, and take a verified full backup immediately before patching.
  • For Always On environments, use a rolling upgrade approach to minimise downtime during the maintenance window.
  • SQL Server 2014 reached end of extended support in July 2024. Applying these CUs addresses known issues but does not replace a migration plan to a supported version.
  • Use SELECT @@VERSION and SERVERPROPERTY('ProductVersion') to confirm your current build number before and after applying any update.

If your team is managing SQL Server 2014 environments and you're unsure whether your patch levels are current, or you're planning a migration to a newer version, DBA Services can help. Our SQL Server health checks cover patch currency, configuration risk, and upgrade readiness across your entire SQL Server estate. Contact us to find out what's actually running in your environment and what needs attention.