Entity Framework: “Store update, insert, or delete statement affected an unexpected number of rows (0).” [closed]

Answer 1

Wow, lots of answers, but I got this error when I did something slightly different that no on else has mentioned.

Long story short, if you create a new object and tell EF that its modified using the EntityState.Modified then it will throw this error as it doesn't yet exist in the database. Here is my code:

MyObject foo = new MyObject()
{
    someAttribute = someValue
};

context.Entry(foo).State = EntityState.Modified;
context.SaveChanges();

Yes, this seems daft, but it arose because the method in question used to have foo passed to it having been created earlier on, now it only has someValue passed to it and creates foo itself.

Easy fix, just change EntityState.Modified to EntityState.Added or change that whole line to:

context.MyObject.Add(foo);

Answer 2

I started getting this error after changing from model-first to code-first. I have multiple threads updating a database where some might update the same row. I don't know why I didn't have a problem using model-first, assume that it uses a different concurrency default.

To handle it in one place knowing the conditions under which it might occur, I added the following overload to my DbContext class:

using System.Data.Entity.Core.Objects;
using System.Data.Entity.Infrastructure;

public class MyDbContext: DbContext {
...
        public int SaveChanges(bool refreshOnConcurrencyException, RefreshMode refreshMode = RefreshMode.ClientWins) {
            try {
                return SaveChanges();
            }
            catch (DbUpdateConcurrencyException ex) {
                foreach (DbEntityEntry entry in ex.Entries) {
                    if (refreshMode == RefreshMode.ClientWins)
                        entry.OriginalValues.SetValues(entry.GetDatabaseValues());
                    else
                        entry.Reload();
                }
                return SaveChanges();
            }
        }
}

Then called SaveChanges(true) wherever applicable.

Answer 3

I also had this error. There are some situations where the Entity may not be aware of the actual Database Context you are using or the Model may be different. For this, set: EntityState.Modified; to EntityState.Added;

To do this:

if (ModelState.IsValid)
{
context.Entry(yourModelReference).State = EntityState.Added;
context.SaveChanges();
}

This will ensure the Entity knows youre using or adding the State youre working with. At this point all the correct Model Values need to be set. Careful not to loose any changes that may have been made in the background.

Hope this helps.

Answer 4

I got this error sporadically when using an async method. Has not happened since I switched to a synchronous method.

Errors sporadically:

[Authorize(Roles = "Admin")]
[HttpDelete]
[Route("file/{id}/{customerId}/")]
public async Task<IHttpActionResult> Delete(int id, int customerId)
{
    var file = new Models.File() { Id = id, CustomerId = customerId };
    db.Files.Attach(file);
    db.Files.Remove(file);

    await db.SaveChangesAsync();

    return Ok();
}

Works all the time:

[Authorize(Roles = "Admin")]
[HttpDelete]
[Route("file/{id}/{customerId}/")]
public IHttpActionResult Delete(int id, int customerId)
{
    var file = new Models.File() { Id = id, CustomerId = customerId };
    db.Files.Attach(file);
    db.Files.Remove(file);

    db.SaveChanges();

    return Ok();
}

Answer 5

I got this exception when attaching an object that didn't exist in the database. I had assumed the object was loaded from a separate context, but if it was the user's first time visiting the site, the object was created from scratch. We have auto-incrementing primary keys, so I could replace

context.Users.Attach(orderer);

with

if (orderer.Id > 0) {
    context.Users.Attach(orderer);
}

Answer 6

I had the same problem. In my case I was trying to update the primary key, which is not allowed.