LINQ To SQL error "There is already an open DataReader associated with this Command"

Question

There is already an open DataReader associated with this Command

I am getting this error when I retrieve data from the DataContext object.

How can this be fixed?

You need to show how you use and dispose the DataConext – Mathias F Jun 19 '10 at 16:14 — Mathias F, Jun 19 '10 at 16:14

score 5 · Answer 1 · answered Jun 19 '10 at 14:54

Ensure that you're not declaring your DataContext as static. Create and destroy your DataContext on each use.

public MyDataClass{

    CustomerDataContext db;

    public void MyDataClass()
    {
       db = new CustomerDataContext();
    }

    public Customer GetCustomer(int id)
    {
       return db.Customers.SingleOrDefault(c=>c.ID == id);
    }
}

score 1 · Answer 2 · edited May 23 '17 at 11:48

1

Check this post

Is mixing ADO.NET and LINQ-TO-SQL bad? My data layer isn't working

It realy depends how you store, access and dispose the datacontext. Try to reproduce the error using a load test tool. I use jmeter. Lots of people don't know that they have this issue, because they have too little traffic.

edited May 23 '17 at 11:48

Community

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answered Jun 19 '10 at 16:17

Mathias F

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score 0 · Answer 3 · answered Jun 19 '10 at 14:37

0

You have forget to close the DataReader, and you start one more DataReader on the same connection.

answered Jun 19 '10 at 14:37

Aristos

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score 0 · Answer 4 · edited Dec 10 '18 at 10:55

0

What helped me was converting all the IQueryable types associated with the query that is throwing the error to more native types before using them in another query.

edited Dec 10 '18 at 10:55

adiga

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answered Dec 10 '18 at 10:38

philani-allan mbeje

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LINQ To SQL error "There is already an open DataReader associated with this Command"

4 Answers4