问题背景描述：

1、 run DBCO and new one database connection of MS SQL SERVER :
+++EHR MSS sa MSSQL_SERVER=172.16.105.192 MSSQL_DBNAME=sHR860DemoV2 OBJECT_SOURCE=sHR860DemoV2
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2. RUN SE38 ADBC_TEST_CONNECTION
DB Connection Name +++EHR
the result as follow ：

Testing a Database Connection Defined in DBCON

Could not open connection +++EHR
DBI error 16 occured.
See trace file for further info: dev_w5

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以上问题的解决方案：

DBI error 16 may have several different root causes, this kind of error messages are caused by the usage of invalid and incorrectly configured 'Microsoft SQL Server' DBSL library and ODBC Unix driver components at Linux OS (x86_64) server level.

To clarify and to solve the problem I recommend your SAP Basis and Linux OS engineer carefully check following points :

[1].
For an SAP NetWeaver ABAP system to be able to connect to a remote Microsoft SQL Server database (IaaS), two SW components must be installed in the Linux OS server which the SAP ABAP instance reside on:

1.1 The LIB_DBSL kernel component for Linux OS on x86_64 64bit and MS SQL Server (file dbmssslib.so).

1.2 The Microsoft ODBC driver for Linux x86_64 (see point 2 below).

1.3 Once the tw SW components are installed in the Linux OS server, transaction DBCO will have to be configured in the ABAP system according to SAP note 178949:

178949 - MSSQL: Database MultiConnect

Only the Microsoft SQL Server 'Enterprise Edition' is supported by, Standard and Developer Edition are not supported, as explained in SAP NW Installation guide and note 62988.

[2].
I recommend the SAP Basis and Linux OS engineers make sure that the Linux OS (x86_64) server is cleaned up of previously installed DBSL and ODBC components, and lib* files, and only gets installed the required ones.

- To do that, please have your Linux OS administrator take the time to carefully read and fully apply SAP note 1644499:

1644499 - Database connectivity from Linux to SQL Server

- Make also sure you create the required "symbolic links".

Read also following SAP note:

2656107 - Support for Microsoft ODBC Drivers for SQL Server in SAP NetWeaver

- Make sure you install the valid ODBC driver version;

This will help ensure the SAP NetWeaver and Linux OS server run the correct ODBC version.

Please be also aware that SAP NETWEAVER/DBCO only supports remote connection to Microsoft SQL Server "IaaS", that is remote connection to 'Microsoft SQL Server' RDBMS installed in physical or virtual machines like VMware, Microsoft Azure and AWS (Xen/KVM).
Remote connections to Azure SQL database is not supported, as explained in note 249714,

2497147 - SAP DBSL connectivity to Microsoft "SQL" or "SQL Server" branded products