Hangfire: Azure SQL: Adding a new job is failing - distributed-transactions

Question

Getting the below error
Inner Exception: "Object reference not set to an instance of an object."
Stack Trace:
at System.Transactions.Transaction.GetPromotedToken()
The error comes from the line connection.EnlistTransaction(Transaction.Current); in below code even if i set enlist=false in the connection string.
`internal T UseTransaction<T>([InstantHandle] Func<DbConnection, DbTransaction, T> func, IsolationLevel? isolationLevel)
{
#if NETFULL
using (var transaction = CreateTransaction(isolationLevel ?? _options.TransactionIsolationLevel))
{
var result = UseConnection(connection =>
{
connection.EnlistTransaction(Transaction.Current);
return func(connection, null);
});
transaction.Complete();
return result;
}
}`
when we set enlist=true, then we get error at the line connection.Open(); from the below code
internal DbConnection CreateAndOpenConnection()
{
if (_existingConnection != null)
{
return _existingConnection;
}
var connection = new SqlConnection(_connectionString);
connection.Open();
return connection;
}
both the methods are present under Hangfire.SqlServer.SqlServerStorage class
Same code works when connected to the local DB (SQL server 2014).
Landed on a discussion WCF Transaction against Azure SQL DB, not sure if it is relevant for this issue.
Edit:
HangFire Configuration
GlobalConfiguration.Configuration.UseSqlServerStorage(
Database.ConnectionString,
new SqlServerStorageOptions
{
QueuePollInterval = TimeSpan.FromSeconds(10),
PrepareSchemaIfNecessary = true
});
Job Enqueue
BackgroundJob.Enqueue(() => Update(connectionToken, intFileUniqueId));
Please help.
Thanks in advance.

Answer 1

Found the issue. call to method to queue job was inside transaction which was somehow leading to Distribution Transaction and Azure SQL doesn't support it.
Consider the code below:
public override void UpdateFile(int intUniqueId)
{
using (var scope = GetTransactionScope(...))
{
QueueJob<Updater>(x => x.Update(token, intUniqueId));
scope.Complete();
}
}
private static void QueueJob<T>(Expression<Action<T>> action)
{
BackgroundJob.Enqueue(action);
}
Removing the transaction scope in callee method works.
I'm checking the necessity of the transaction scope, if not required, I'll remove it.!!!