---
title: "SQL Server 2025 release notes"
description: Find information about SQL Server 2025 (17.x) limitations, known issues, help resources, and other release notes.
author: MikeRayMSFT
ms.author: mikeray
ms.reviewer: randolphwest
ms.date: 04/20/2025
ms.service: sql
ms.subservice: release-landing
ms.topic: release-notes
monikerRange: ">= sql-server-2016"
ms.custom:
  - build-2025
---

# SQL Server 2025 Preview release notes

[!INCLUDE[sqlserver2025](../includes/applies-to-version/sqlserver2025.md)]

This article describes requirements, limitations, and known issues for [!INCLUDE[sssql25-md](../includes/sssql25-md.md)].

## Hardware and software requirements

For hardware and software requirements, see [SQL Server 2025: Hardware and software requirements](install/hardware-and-software-requirements-for-installing-sql-server-2025.md).

## Known issues

### SQL Server fails to start after installation

**Issue**: SQL Server instances on Windows might fail to start after the installation if the machine has more than 64 logical cores per NUMA node.

For more information, see [Limit number of logical cores per NUMA node to 64](compute-capacity-limits-by-edition-of-sql-server.md#limit-number-of-logical-cores-per-numa-node-to-64).

### Upgrade in place

[!INCLUDE [sssql25-md](../includes/sssql25-md.md)] doesn't support in place upgrades from previous versions of [!INCLUDE [ssnoversion-md](../includes/ssnoversion-md.md)], including SQL Server 2025 CTP releases.

### Setting the backup compression algorithm to ZSTD

There's a known issue when attempting to set the [backup compression algorithm](../database-engine/configure-windows/view-or-configure-the-backup-compression-algorithm-server-configuration-option.md) to ZSTD. 

When specifying the ZSTD algorithm (`backup compression algorithm = 3`), the following error message returns:

```console
Msg 15129, Level 16, State 1,  Procedure sp_configure `3` is not a valid value for configuration option 'backup compression algorithm'. 
```

Use the new compression algorithm directly in the [BACKUP](../t-sql/statements/backup-transact-sql.md#-compression---algorithm---ms_xpress--zstd--accelerator_algorithm---level---low--medium--high------no_compression-) Transact-SQL command instead of setting the server configuration option.

### Incorrect behavior of SESSION_CONTEXT in parallel plans

Queries that use the built-in `SESSION_CONTEXT` function may return incorrect results or trigger access violation (AV) dumps when executed in parallel query plans. This issue stems from the way `SESSION_CONTEXT` interacts with parallel execution threads, particularly when the session is reset for reuse.

For more information, see the [Known issues](../t-sql/functions/session-context-transact-sql.md#known-issues) section in `SESSION_CONTEXT`.

## Build number

| Build | Version number | Date |
| --- | --- | --- |
| Preview | 17.0.700.9 | May 19, 2025 |

## Related content

- [What's new in SQL Server 2025 Preview](what-s-new-in-sql-server-2025.md)