TITLE: Connect to Server
------------------------------
Cannot connect to Thejus-PC.
------------------------------ ADDITIONAL INFORMATION:
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)
> (.Net SqlClient Data Provider)
>
> ------------------------------ For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft%20SQL%20Server&EvtSrc=MSSQLServer&EvtID=2&LinkId=20476
>
> ------------------------------ Error Number: 2 Severity: 20 State: 0
>
>
> ------------------------------ Program Location:
>
> at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException
> exception, Boolean breakConnection, Action`1 wrapCloseInAction) at
> System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject
> stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) at
> System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo,
> SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout,
> Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean
> integratedSecurity, Boolean withFailover, SqlAuthenticationMethod
> authType) at
> System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo
> serverInfo, String newPassword, SecureString newSecurePassword,
> Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean
> withFailover) at
> System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo
> serverInfo, String newPassword, SecureString newSecurePassword,
> Boolean redirectedUserInstance, SqlConnectionString connectionOptions,
> SqlCredential credential, TimeoutTimer timeout) at
> System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer
> timeout, SqlConnectionString connectionOptions, SqlCredential
> credential, String newPassword, SecureString newSecurePassword,
> Boolean redirectedUserInstance) at
> System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity
> identity, SqlConnectionString connectionOptions, SqlCredential
> credential, Object providerInfo, String newPassword, SecureString
> newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString
> userConnectionOptions, SessionData reconnectSessionData,
> DbConnectionPool pool, String accessToken) at
> System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions
> options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo,
> DbConnectionPool pool, DbConnection owningConnection,
> DbConnectionOptions userOptions) at
> System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection
> owningConnection, DbConnectionPoolGroup poolGroup, DbConnectionOptions
> userOptions) at
> System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection
> owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions
> userOptions, DbConnectionInternal oldConnection, DbConnectionInternal&
> connection) at
> System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection
> outerConnection, DbConnectionFactory connectionFactory,
> TaskCompletionSource`1 retry, DbConnectionOptions userOptions) at
> System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection
> outerConnection, DbConnectionFactory connectionFactory,
> TaskCompletionSource`1 retry, DbConnectionOptions userOptions) at
> System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1
> retry) at
> System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1
> retry) at System.Data.SqlClient.SqlConnection.Open() at
> Microsoft.SqlServer.Management.SqlStudio.Explorer.ObjectExplorerService.ValidateConnection(UIConnectionInfo
> ci, IServerType server) at
> Microsoft.SqlServer.Management.UI.ConnectionDlg.Connector.ConnectionThreadUser()
>
> ===================================
>
> The system cannot find the file specified
Please verify that Service "SQL Server (MSSQLSERVER)" is started.
I started the "SQL Server (MSSQLSERVER)" service and now i am able get into Sql server.
Ramakrishnankt
Please verify that Service "SQL Server (MSSQLSERVER)" is started. Just now I upgraded to Windows 10 and got the same issue.
I started the "SQL Server (MSSQLSERVER)" service and now I am able get into Sql server.
We have encountered this problem with Windows 7 and Windows 8. After the upgrade SQL Server does not start. We have been able to start it manually, but it will not start automatically.
So far our only solution has been to uninstall and reinstall SQL Server.
Try changing your connection string to IP/NameInstance, it works for me. Before I used to have localhost/NameInstance in my connection string but since I updated to windows 10, it did not work anymore.
来源：https://stackoverflow.com/questions/31737231/sql-server-not-working-after-upgrading-windows8-1-to-windows-10