想问一下项目中出现这个错误是怎么回事

System.Data.SqlClient.SqlException: '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. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)'
这个是错误提示的全部信息，谁能指导一下，我这个是什么问题吗？

System.Data.SqlClient.SqlException: '在建立到SQL Server的连接时发生了与网络相关或与实例相关的错误。找不到服务器或无法访问服务器。验证实例名是否正确，SQL Server是否配置为允许远程连接。(提供程序:Named Pipes提供程序，错误:40 -无法打开到SQL Server的连接)'
百度翻译一下