Error when connect database continuously

When I am querying from database in continuous looping, after some time I get an error :

An exception has been raised that is likely due to a transient failure. If you are connecting to a SQL Azure database consider using SqlAzureExecutionStrategy.

Normally it is working fine.

If you are using EF Core configure retry on failure for resilient connections :

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    optionsBuilder.UseSqlServer("your_connection_string", builder =>
        {
            builder.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
        });
    base.OnConfiguring(optionsBuilder);
}

When connecting to a SQL Database you have to account for transient connection failures. These connection failures can happen for example when updates are rolled out, hardware fails etc. The error you see indicates that one of these things happened which is why your connection was dropped. Enabling an Execution Strategy as suggested by Anbuj should solve the issue.

Enable an execution strategy as mentioned here : https://msdn.microsoft.com/en-us/data/dn456835.aspx . When designing for Azure SQL DB, you have to design for transient connection failures, since back-end updates, hardware failures, load balancing can cause intermittent failures at times.