Error executing the following:

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: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

Problem: System.Data.SqlClient.SqlException (0x80131904): 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: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   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 SmarterTrack.Data.RoleEntityBase.GetListFromQuery_SQL(IDbConnection& connection, String query, String[] extras, SqlParameter[] parameters)
   at SmarterTrack.Data.RoleEntityBase.GetListFromQuery(IDbConnection& connection, String query, SqlParameter[] parameters)
   at SmarterTrack.Data.RoleEntityBase.GetAll(IDbConnection& connection, String orderby)
   at SmarterTrack.Data.RoleEntityBase.GetAll(String orderby)
   at SmarterTrack.Data.RoleEntityBase.GetDictionary()
   at SmarterTrack.Data.Caching.RoleCache.ReloadCache()
   at SmarterTrack.Data.Caching.CacheArray`2.#5hb()
   at SmarterTrack.Data.Caching.CacheArray`2.GetDictionary()
   at SmarterTrack.Data.Caching.CacheArray`2.GetAll()
   at SmarterTrack.Data.DatabaseUpgrade.#Sib()
   at SmarterTrack.Data.DatabaseUpgrade.EnsureCommonObjectsLoaded()
   at SmarterTrack.HelperClasses.Threads.DatabaseUpgradeThread.ThreadFunc()
ClientConnectionId:00000000-0000-0000-0000-000000000000
Error Number:-1,State:0,Class:20