Error: Connection was attempted with an older version of SQL Server client communications software that is not compatible with the SQL Server database server
Connecting from ArcGIS Desktop or another ArcGIS client to an enterprise geodatabase hosted on SQL Server returns the following error message:
Error: Connection was attempted with an older version of SQL Server client communications software that is not compatible with the SQL Server database server.
This error can occur if there is no SQL Server client communication software installed on the PC, the client software is older than the SQL Server instance (such as using SQL Server Native Client 2008 R2 to connect to SQL Server 2012), or the username/password entered when establishing a database connection is incorrect. ArcGIS requires that the database client software managing communication between the application and SQL Server is at least as new as the SQL Server instance to which it is connecting. This prevents any problems that may arise when the database client software does not understand new data types introduced in the newer databases.
Since Native Client 2012 is the last version to be released by Microsoft at the time of this writing, the version still satisfies the requirement when connecting to SQL Server 2014 and 2016. SQL Server client software is required for any ArcGIS Desktop machine making a database connection to SQL Server. This includes ArcSDE servers to support an application server connection. Microsoft attempts to make its client drivers backward compatible to older releases. However, Microsoft client drivers are not necessarily forward compatible.
Microsoft ODBC Driver 13 can be used for connections to SQL Server 2016, as well. A connection to a Windows Azure SQL database requires Microsoft ODBC Driver 11 for SQL Server.
Solution or Workaround
Install the appropriate SQL Server client communication software, whether it be the native client or ODBC driver. To encompass as many mixed environment possibilities, install the SQL Server Native Client 2012 to connect. This can be used to connect to SQL Server 2008, 2008 R2, 2012, 2014, and 2016 from all supported versions of ArcGIS Desktop. Microsoft ODBC Driver 11 can be used for this requirement, as well. Both the Microsoft ODBC Driver 11 for SQL Server and the SQL Server Native Client 2012 are available for download from Microsoft. Copies can also be found on the My Esri portal under the Downloads section.