Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached."
Message from the system: "Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached." Always close your connection in the final block: or Increase pool size like in your connection string string connectionString = "Data Source=localhost; Initial Catalog=Northwind;" + "Integrated Security=SSPI; Min Pool Size=10; Max Pool Size=100"; Don't use pooling string connectionString = "Data Source=localhost; Initial Catalog=Northwind;" + "Integrated Security=SSPI; Pooling=false;";