title: SQL Connection Error: System.Data.SqlClient.SqlException (0x80131904)
body: <p>I am seeing this in several situations and it is intermittent in our web based application  connecting to SQL 2008 R2 serve back end. Users are coming across a point 2 point connection and seeing this on and off. Thought it was bandwidth issues until I started seeing it on terminal servers that are on the same core switch as this SQL server. I have checked remote connection enabled, Port 1433 is set correctly in Configuration for TCP/IP and the only thing I see that could be a cause is the timeout setting is set to 100000 in the remote connections rather than unlimited. </p>
  
  <p>The error is </p>
  
  <blockquote>
    <p><code>System.Data.SqlClient.SqlException</code> (<code>0x80131904</code>): <em>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)</em> <code>---&gt;</code></p>
    
    <p><code>System.ComponentModel.Win32Exception</code> (<code>0x80004005</code>): <em>The network path
    was not found</em> <code>at</code></p>
    
    <pre class="lang-none prettyprint-override"><code>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) 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) at
  System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions
  options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo,
  DbConnectionPool pool, DbConnection owningConnection,
  DbConnectionOptions userOptions) at
  System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool
  pool, DbConnection owningObject, DbConnectionOptions options,
  DbConnectionPoolKey poolKey, DbConnectionOptions userOptions) at
  System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection
  owningObject, DbConnectionOptions userOptions, DbConnectionInternal
  oldConnection) at
  System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection
  owningObject, DbConnectionOptions userOptions, DbConnectionInternal
  oldConnection) at
  System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection
  owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean
  allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions
  userOptions, DbConnectionInternal&amp; connection) at
  System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection
  owningObject, TaskCompletionSource`1 retry, DbConnectionOptions
  userOptions, DbConnectionInternal&amp; connection) at
  System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection
  owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions
  userOptions, DbConnectionInternal oldConnection, DbConnectionInternal&amp;
  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
  System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.&lt;&gt;c__DisplayClass1.b__0()
  at
  System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1
  operation) at
  System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action
  operation) at
  System.Data.Entity.Core.EntityClient.EntityConnection.Open()
  ClientConnectionId:00000000-0000-0000-0000-000000000000
  </code></pre>
  </blockquote>