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KB5093421 - Cumulative Update 6 for SQL Server 2025

  • Applies to: SQL Server 2025 on Windows, SQL Server 2025 on Linux

Release Date:   June 17, 2026
Version:   17.0.4055.5

Summary

This article describes Cumulative Update (CU6) for Microsoft SQL Server 2025. This update package contains 19 fixes that were issued after the release of SQL Server 2025 Cumulative Update 5. It updates components in the following builds:

  • SQL Server - Product version: 17.0.4055.5, file version: 2025.170.4055.5
  • Analysis Services - Product version: 17.0.25.223, file version: 2025.170.25.223

Important

To help secure SQL Server on Windows, enable encryption with Extended Protection.

Known issues in this update

Incorrect behavior of SESSION_CONTEXT in parallel plans

Queries that use the built-in SESSION_CONTEXT function might return incorrect results or trigger access violation (AV) dump files when run in parallel query plans. This issue occurs because of the manner in which SESSION_CONTEXT interacts with parallel execution threads, particularly if the session is reset for reuse.

For more information, see the Known issues section in SESSION_CONTEXT.

Linked server queries that use MSDASQL fail and generate error 7416

Linked server queries that use the MSDASQL (OLE DB Provider for ODBC Drivers) provider and specify a provider string (@provstr) fail and return the following error message:

Msg 7416, Level 16
Access to the remote server is denied because no login-mapping exists.

A stricter connection validation check in the Database Engine can reject connections for certain linked server configurations that use the MSDASQL provider, even if earlier builds allowed those connections.

For more information and workarounds, see Linked server queries that use MSDASQL fail with error 7416.

Improvements and fixes included in this update

A downloadable Microsoft Excel workbook that contains a summary list of builds, together with their current support lifecycle, is available. The Excel file also contains detailed fix lists for SQL Server 2025, SQL Server 2022, SQL Server 2019, and SQL Server 2017. Download this Excel file now.

Note

Individual entries in the following table can be referenced directly through a bookmark. If you select any bug reference ID in the table, a bookmark tag is added to the URL by using the "#NNNNNNN" format. You can then share this URL with others so that they can jump directly to the desired fix in the table.

For more information about the bugs that are fixed and enhancements that are included in this cumulative update, see the following table.

Bug Reference Description Fix Area Component Platform
5094785 Fixes an issue that can occur during parallel vector index builds and that can cause resource exhaustion and performance degradation. SQL Server Engine Query Processing All
5152151 Fixes an issue in which changing the collation setup can block mssql-conf unexpectedly on systems that have a high CPU count. SQL Server Engine Linux Linux
5195494 Fixes an issue in which altering a disabled DDL trigger causes a memory access violation. SQL Server Engine Programmability All
5200910 Fixes an issue in which file creation fails unexpectedly on file systems that don't support hard links. SQL Server Engine Linux Linux
5218020 Updates the Pacemaker resource agent to treat a forwarder replica as the local primary for the local availability group orchestrator. SQL Server Engine High Availability and Disaster Recovery Linux
5218889 Fixes Error 17750 (DLL load failure) that can occur when you run sp_executesql in a Linux container that's configured by using the Korean_Wansung_CI_AS collation. SQL Server Engine Linux Linux
5221609 Fixes a failure that can occur on Linux when you run striped backups that have 16 or more stripes if Transparent Huge Pages (THP) is enabled. SQL Server Engine Linux Linux
5228161 Adds more detailed error information to the Windows Failover Cluster log when the availability group resource DLL can't retrieve diagnostic column information. SQL Server Engine High Availability and Disaster Recovery Windows
5229575 Fixes a scheduling issue that can prevent a thread from suspending during an index rebuild. This issue causes the program to stop responding. SQL Server Engine Linux Linux
5240442 Changes the default value of the FULLTEXT_INDEX_VERSION database scoped configuration to 2 on Azure SQL Managed Instance. SQL Server Engine Search Windows
5240590 Fixes an issue in which DDL operations on Change Data Capture (CDC) tables can trigger date conversion errors. SQL Server Engine Linux Linux
5248649 Updates the bcp utility to support bulk import and bulk export of the vector(16) and vector(32) data types. Support for vector(16) in bcp becomes functional only after the next ODBC driver release. Also adds the -H (HostNameInCertificate) and -J (ServerCertificate) options for strict TLS certificate validation. SQL Connectivity SQL Connectivity Windows
5251310 Fixes several issues that can cause tempdb space usage accounting to be inaccurate in uncommon cases. SQL Server Engine SQL OS All
5255250 Upgrades SQL Server Integration Services (SSIS) password-based encryption (EncryptAllWithPassword and EncryptSensitiveWithPassword) to use PBKDF2 with SHA-256 and 100,000 iterations for packages that target SQL Server 2025. Packages that are saved after this update, including packages that are generated by the Import and Export Wizard, require compatible versions of SQL Server Data Tools (SSDT) and SQL Server Management Studio (SSMS) to open. Until Microsoft releases compatible versions, users can't open these packages in SSDT or SSMS. For compatible versions, see the SSDT and SSMS release notes. Packages that target SQL Server 2022 and earlier versions aren't affected. Integration Services Integration Services Windows
5256562 Fixes a failed assertion that's related to thread trace elements that can occur on the primary replica of an availability group. SQL Server Engine High Availability and Disaster Recovery All
5258873 Fixes an issue in which SSIS packages can't be deployed or run successfully if they connect to SQL Server instances that are configured by using Encrypt=Strict. Integration Services Integration Services Windows
5266605 Fixes handling of zero-length TLS records in the SNI SSL provider. SQL Server Engine Unified Communication Stack All
5267380 Fixes a possible failure that can occur on a DML operation that inserts a NULL JSON document into a JSON index column. SQL Server Engine Programmability All
5270750 Deprecates full-text index version 1 on Azure SQL Managed Instance. SQL Server Engine Search Windows

How to obtain or download this CU or the latest CU package

How to obtain or download the latest cumulative update package for Windows (recommended)

The following update is available from the Microsoft Download Center:

Download the latest cumulative update package for SQL Server 2025 now

Note

  • Microsoft Download Center always offers the latest SQL Server 2025 CU release.
  • If the download page doesn't appear, contact Microsoft Customer Service and Support to obtain the cumulative update package.
How to obtain or download this cumulative update package for Windows from Microsoft Update Catalog

The following update is available from the Microsoft Update Catalog:

Note

  • Microsoft Update Catalog contains this SQL Server 2025 CU and previously released SQL Server 2025 CU releases.
  • This CU is also available through Windows Server Update Services (WSUS).
  • We recommend that you always install the latest cumulative update that's available.
How to obtain or download the latest cumulative update package for Linux

To update SQL Server 2025 on Linux to the latest CU, you must first have the Cumulative Update repository configured. Then, update your SQL Server packages by using the appropriate platform-specific update command.

For installation instructions and direct links to the CU package downloads, see the SQL Server 2025 Release Notes.

File information

File hash information

You can verify the download by computing the hash of the SQLServer2025-KB5093421-x64.exe file through the following command:

certutil -hashfile SQLServer2025-KB5093421-x64.exe SHA256

File name SHA256 hash
SQLServer2025-KB5093421-x64.exe 1D91082726FD4331F7D48FF992BA3C7511599F881FBE3ABE431148AA9CE74441
Cumulative Update package file information

Download the list of files that are included in KB5093421.

Notes for this update

Prerequisites

To apply this cumulative update package, you must be running SQL Server 2025.

Restart information

You might have to restart the computer after you apply this cumulative update package.

Registry information

To use one of the hotfixes in this package, you don't have to make any changes to the registry.

Important notices

This article also provides the following important information.

Analysis Services CU build version

Beginning in Microsoft SQL Server 2017, the Analysis Services build version number and SQL Server Database Engine build version number don't match. For more information, see Verify Analysis Services cumulative update build version.

Cumulative updates (CU)

  • Each new CU contains all the fixes that were included in the previous CU for the installed version of SQL Server.
  • SQL Server CUs are certified to the same levels as service packs, and should be installed at the same level of confidence.
  • We recommend ongoing, proactive installation of CUs as they become available according to these guidelines:
    • Historical data shows that a significant number of support cases involve an issue that was already addressed in a released CU.
    • CUs might contain added value over and above hotfixes, such as supportability, manageability, and reliability updates.
  • We recommend that you test SQL Server CUs before you deploy them to production environments.
Hybrid environment deployment

When you deploy an update to a hybrid environment (such as Always On, replication, cluster, and mirroring), we recommend that you refer to the following articles before you deploy the update:

Language support

SQL Server CUs are currently multilingual. Therefore, this CU package isn't specific to one language. It applies to all supported languages.

Components (features) updated

One CU package includes all available updates for all SQL Server 2025 components (features). However, the cumulative update package updates only those components that are currently installed on the SQL Server instance that you select to be serviced. If a SQL Server feature (for example, Analysis Services) is added to the instance after this CU is applied, you must reapply this CU to update the new feature to this CU.

Support for this update

If other issues occur, or if any troubleshooting is required, you might have to create a service request. The usual support costs will apply to additional support questions and to issues that don't qualify for this specific cumulative update package. For a complete list of Microsoft Customer Service and Support telephone numbers, or to create a separate service request, go to the Microsoft support website.

How to uninstall this update

How to uninstall this update on Windows
  1. In Control Panel, open the Programs and Features item, and then select View installed updates.
  2. Locate the entry that corresponds to this cumulative update package under SQL Server 2025.
  3. Press and hold (or right-click) the entry, and then select Uninstall.
How to uninstall this update on Linux

To uninstall this CU on Linux, you must roll back the package to the previous version. For more information about how to roll back the installation, see Rollback SQL Server.

References

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