Breaking Changes to Database Engine Features in SQL Server 2017 (14.x)
This topic describes breaking changes in the SQL Server 2017 (14.x) Database Engine. These changes might break applications, scripts, or functionalities that are based on earlier versions of SQL Server. You might encounter these issues when you upgrade.
Breaking Changes in SQL Server 2017 (14.x) Database Engine
CLR uses Code Access Security (CAS) in the .NET Framework, which is no longer supported as a security boundary. Beginning with SQL Server 2017 (14.x)Database Engine, an
clr strict securityis introduced to enhance the security of CLR assemblies. clr strict security is enabled by default, and treats
EXTERNAL_ACCESSCLR assemblies as if they were marked
clr strict securityoption can be disabled for backward compatibility, but this is not recommended. When
clr strict securityis disabled, a CLR assembly created with
PERMISSION_SET = SAFEmay be able to access external system resources, call unmanaged code, and acquire sysadmin privileges. After enabling strict security, any assemblies that are not signed will fail to load. Also, if a database has
ATTACH DATABASEstatements can complete, but the assemblies may fail to load.
To load the assemblies, you must either alter or drop and recreate each assembly so that it is signed with a certificate or asymmetric key that has a corresponding login with the
UNSAFE ASSEMBLYpermission on the server. For more information, see CLR strict security.
The MD2, MD4, MD5, SHA, and SHA1 algorithms are deprecated in SQL Server 2016 (13.x). Up to SQL Server 2016 (13.x), a self-signed certificate is created using SHA1. Starting with SQL Server 2017 (14.x), a self-signed certificate is created using SHA2_256.
Archived Documentation for Very Old Versions of SQL Server
We accumulate and retain documentation for very old versions of Microsoft SQL Server, in sets of archived webpages. The archived webpages are not processed by search engines, such as Bing.com and Google.com. Yet you can see these archives at our Docs previous-versions/sql/ address:
These archives include the documentation for at least the following older versions:
- SQL Server 2014
- SQL Server 2012
- SQL Server 2008 R2
- SQL Server 2008
- SQL Server 2005
SQL Server 2014 documentation is still available on our main Docs address.
SQL Server 2019 documentation is available on our main Docs address. Then use the versioning dropdown near the top of the page, to select another version of interest.
For more information about the documentation for previous versions of SQL Server, see Previous versions of SQL Server documentation.
Deprecated Database Engine Features in SQL Server 2016
Discontinued Database Engine Functionality in SQL Server 2016
SQL Server Database Engine Backward Compatibility
ALTER DATABASE Compatibility Level (Transact-SQL)