Fix: A Network-Related Instance Specific Error Occurred – Error 26 Microsoft SQL Server
If you suddenly receive an SQL connection error, it may be related to a recent DNS change in your network. The error message as follows.
A network-related or instance-specific error occurred while establishing a connection to SQL server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (providers: SQL Network Interfaces, error: 26 – Error Locating Server/Instance Specified) (Microsoft SQL Server)
The error is specific to a connection issue so it can be related to numerous issues; however, check to ensure the DNS setup point to the SQL Instance/Server still exists and is correct.