Error: [DBNETLIB] SQL Server does not exist or access denied.

Source: Microsoft OLE DB Provider for SQL Server

Number: -2147467259

Error: [DBNETLIB] [ConnectionOpen (Connect().]SQL Server does not exist or access denied

when first time running ERPro Desktop Client on a workstation.

Either

1. Make sure the SQL Server Name, System Database, SQL User ID and SQL User Password is correct.

2. Allow Remote Connection if the SQL Server installed is Express Edition

How to configure SQL Server 2005 Express to allow remote connections?

3. Turn off Windows Firewall of the SQL server or Create SQL Server exceptions in Windows Firewall

4. Make sure the SQL Server Browser Service is running

If this is not the first time running ERPro Desktop Client on a workstation.

Make sure the SQL Server is not down
The SQL Server Name, System Database, SQL User ID and SQL User Password is correct
The SQL connection is not blocked by the workstation firewall or SQL server firewall
1. Make sure the SQL Server Browser Service is running
The system database and application database is accessible.

2018/05/29

P.S. If the ERPro desktop client is installed on a Windows 10 desktop, and the error occurred just after the Windows 10 is upgraded to Windows 10 build 1803 (run winver from search box to determine the Windows build version) by Windows Update, then it is because the security control of Windows 10 build 1803 blocked the network connection of the ERPRO.EXE that started from an untrusted location (i.e. the network shared folder using SMB1.5 or below). Copy the ERPro shared folder to local hard disk and start ERPro from the local hard disk is a workaround.

Otherwise consider the followings

If the File Server is Windows Server 2003, upgrade the Server to Windows 2008 R2 or above and activate SMB2 (or above) on that server. Microsoft is ended the support for Windows Server 2003 on July 14, 2015
Move the ERPro shared folder to a File Server or NAS that supported SMB2
Use Named Pipes to connect to the SQL Server other than TCP/IP
Install other Anti-virus program to replace Microsoft Windows Defender
Apply Emergency Hot Fix for Windows 10 1803 KB4284848 (2018/06/26)