Entity Framework with SQLite exception: The underlying provider failed on Commit

Question

I'm using the Entity Framework (.NET 4.0) with SQLite as the underlying database and I get an exception when I try to commit some changes to the database:

The underlying provider failed on Commit.

The stack trace is:

System.Data.EntityException: The underlying provider failed on Commit. ---> System.Data.SQLite.SQLiteException: The database file is locked
database is locked
   at System.Data.SQLite.SQLite3.Step(SQLiteStatement stmt)
   at System.Data.SQLite.SQLiteDataReader.NextResult()
   at System.Data.SQLite.SQLiteDataReader..ctor(SQLiteCommand cmd, CommandBehavi
or behave)
   at System.Data.SQLite.SQLiteCommand.ExecuteReader(CommandBehavior behavior)
   at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery()
   at System.Data.SQLite.SQLiteTransaction.Commit()
   at System.Data.EntityClient.EntityTransaction.Commit()
   --- End of inner exception stack trace ---
   at System.Data.EntityClient.EntityTransaction.Commit()
   at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
   at MySystem.MySystemService.UpdateFollowersAndUsers() in C:\Path\To\MySystem\MySystemService.cs:line 295

My code is pretty simple:

// Gets more followers for the competitor and updates the database
List<Follower> moreFollowers = GetMoreFollowers(competitor);

// Add the new followers to the database
using (MySystemEntities db = new MySystemEntities())
{
    try
    {
        foreach (Follower f in moreFollowers)
        {
            db.AddToFollowers(f);
        }
        db.SaveChanges();
    }
    catch (Exception e)
    {
        Console.WriteLine(e.ToString());
    }
}

This snippet of code is inside MyService , it comes in with a batch of 5,000 followers and it's getting the above exception. However, when I pull the same snippet of code out into the Main function and just manually add a few followers, then it no longer throws the exception and the followers are successfully added to my database. Apparently the database file is locked, what may be causing this issue?

Answer 1

I just found out the answer in another SO question: 'The database file is locked' with System.Data.SQLite

Ironically, the OP answers his own question too :).