How to fix System.Data.SqlClient.SqlException: Transaction context in use by another session error?

Question

C++ / C#

task:
on the sql side, a transaction is opened inside which something happens.
inside this transaction, you need to call the clr procedure in C #, which will write something somewhere
, and if the transaction is rolled back, the actions that were performed during the operation of the clr function
should not be rolled back.
for the test, I threw a method in C #

namespace Future.SQLCLR
{
    public class Exception
    {
        public static string ConnectionString
        {
            get
            {
                //string ret = "context connection = true";//
                string ret = "Data Source = server; Initial Catalog = database; Integrated Security = True";
                return ret;
            }
        }


        [SqlFunction()]
        public static void TestInsert(SqlString inputParam)
        {
            using (var cn = new SqlConnection(ConnectionString))
            {
                try
                {
                    cn.ConnectionString = "Enlist=false";

                    cn.Open();
                    
                    var cmd = new SqlCommand("insert into table(field)" +
                       "select field from table_1", cn);

                    cmd.ExecuteNonQuery();
                }
                catch (System.Exception)
                {

                    throw;
                }
                finally
                {
                    cn.Close();
                }
            }
        }
    }
.......
}

CREATE PROCEDURE [audit].[TestInsert]
(
  @msg   nvarchar(2048)
)
AS EXTERNAL NAME CLR.[SQLCLR.Exception].TestInsert

begin tran

exec [TestInsert] 'msg'

rollback

I get the error System.Data.SqlClient.SqlException: Transaction context in use by another session.

Answer 1

Confuses the description of the stored procedure - is it some part of it? Or what is it?

CREATE PROCEDURE [dbo].[MyPROC]
(
  @Param1 nvarchar(2048) out,
  @Param2 int out,
  @Param3 int out,
  @Param4 int
)
AS EXTERNAL NAME DWH_CLR.[Future.SQLCLR.Exception].HandleException