带有SQLite错误的实体框架：从商店提供商的数据读取器读取时发生错误

Question

I'm using SQLite 1.0.89 with EF 5 .NET Framework 4.5 on VS2013 in a WPF application in C#. The DB size is not big and the table that the program use contain max 1000 row.

using the program I found this error often:

An error occurred while reading from the store provider's data reader. See the inner exception for details.

the inner exception is :

{"library routine called out of sequence\\r\\nnot an error"}

Other time the inner exception is:

Connection was closed, statement was terminated

Another time i found:

unknown error\\r\\nno connection handle available

I found this article searching:

Parallel.Foreach loop creating multiple db connections throws connection errors?

SQL Server CE database size issue

but no one solve my problem.

The query that the program do IS NOT inside a loop, but are single query performed when button is pressed on the UI but i noticed that the error happens more often (bun not only) when I press the query button a lot of time faster.

Other thing. The error happens more often (but again not only) when the DB Context is access via a properties istead of a method example:

public List<Product> ProductList
{
get {
      return DBContext.Products.ToList();
    }
}

Answer 1

The problem was caused by multiple thread that query the db using the same DBContext.

Using a different DBContext for each thread solve the problem.

In my case I was using Castle Windsor to inject the DBContext into the class that perform the query. Configuring the lifestyle of the DBContext to one per thread the problem has gone.

Answer 2

I had this error occur in EF6.1 and took me a while to figure out what was going on. Simplified the query, and it worked, so I figured something must be going on in the query. Found out I was querying a string and passing a compare on an int. once I changed the int.toString all worked.

Dim OpenOrder = (From p In context.CP_Carthead Where p.SessionID = MySessionInfo.Current.LeadID.ToString And p.CustomerID = LeadID And p.Deleted = False And p.PortalID = TenantID).OrderBy(Function(p) p.OrderID).FirstOrDefault OrderID = OpenOrder.OrderID

LeadID (my Session) is an int. without the .ToString I get the error in the above post