C# SQLConnection.Open() hangs, with no exception

Question

I am using C# in Visual Studio 2019, with Xamarin.Forms, and SQl in SSMS 2018 and have the below code (where [] is used to replace unneccessary information)

try
{
  using(SqlConnection connection = new SqlConnection())
  {
     connection.ConnectionString = "Server=[ServerName]; Database=[DatabaseName]; User Id= [UserID]; Password=[Password]";

     connection.Open();

     SqlCommand command = new SqlCommand("SELECT * from [TableName]", connection);

     [Does stuff here]
  }
}
catch (Exception ex)
{
  System.Diagnostics.Debug.WriteLine(ex)
}

When I run this, it hangs indefinitely at connection.Open() . Debug mode continues to run and appears to move on from Connection.Open() , but never reaches the next line.

I have attempted this with different versions of the ConnectionString, using different databases and with Trusted_Connection=true instead of specifiying the username and password but they have made no difference. Adding Connection Timeout = 5 to the connectionString has no effect.

I believe it is probably an issue with my settings in SQL but as I am a novice with this I have no idea where to start and the similar forums posts I have checked have been given answers along the lines of Connection Timeout ( Connection.open for hangs indefinitely, no exception is thrown ) or never got answered.

Any advice would be greatly appreciated.

Answer 1

Can you log into SSMS with the credentials that are in the connection string?

Otherwise I've had luck making sure the connection isn't already open or broken first:

if (connection.State == ConnectionState.Closed || connection.State == ConnectionState.Broken)
{
    connection.Open();
}

Answer 2

Can you try code changing line as per below -

connection.ConnectionString = "Data Source=[ServerName]; Initial Catalog=[DatabaseName]; Integrated Security=SSPI;"

Answer 3

A workaround to this problem is to pass in a cancellation token instance as shown below,

public async Task<IEnumerable<Toy>> ShowToybox(CancellationToken t)
{
   // notice I turned this into an async operation. 
   // Reason is to let this operation to find its way out if something happens
    var connString = "Server=xyz; Connection Timeout=250";
    //Timeout might not happen, if that is not the case see below..
    using(SqlConnection connection = new SqlConnection(connString))
    {
        if ( t.IsCancellationRequested) {
            t.ThrowIfCancellationRequested();
        }
       // await query here. To fetch records from the toybox table
       return matches;
     }

Main issue is that you cannot trust connection.State

To get this working, code that consumes this method should expect something might go wrong.

class Program
{
   static void Main()
  {
      var box = new ToxBox(); //it has method shown above
      var s = new CancellationTokenSource();
      s.CancelAfter(400); //it prevents method from hanging
      var task = Task.Run(() = box.ShowToybox(s.Token));
      try
      {
          task.Wait(s.Token);
          var myToys = task.Result();
          Console.WriteLine($"I have {myToys.Count()} toys");
      }
      catch (Exception e)
      {
          Console.WriteLine("Something happened!"); 
      }
      finally
      {
          s.Dispose(); //this is important
      }  
  }
}

See https://docs.microsoft.com/en-us/dotnet/standard/threading/cancellation-in-managed-threads