Getting "The connection does not support MultipleActiveResultSets" in a ForEach with async-await

Question

I have the following code using Dapper.SimpleCRUD :

var test = new FallEnvironmentalCondition[] {
    new FallEnvironmentalCondition {Id=40,FallId=3,EnvironmentalConditionId=1},
    new FallEnvironmentalCondition {Id=41,FallId=3,EnvironmentalConditionId=2},
    new FallEnvironmentalCondition {Id=42,FallId=3,EnvironmentalConditionId=3}
};
test.ToList().ForEach(async x => await conn.UpdateAsync(x));

With this code, I am getting following exception:

InvalidOperationException: The connection does not support MultipleActiveResultSets

I don't understand I am awaiting each update so why am I getting this error.

Note: I have no control on the connection string so I can't turn MARS on.

Answer 1

You need to add attribute MultipleActiveResultSets in connection string and set it to true to allow multiple active result sets.

 "Data Source=MSSQL1;" & _  
    "Initial Catalog=AdventureWorks;Integrated Security=SSPI;" & _  
    "MultipleActiveResultSets=True"  

Read more at: https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/sql/enabling-multiple-active-result-sets