Validation failed for one or more entities while saving changes to SQL Server Database using Entity Framework

You can extract all the information from the DbEntityValidationException with the following code (you need to add the namespaces: System.Data.Entity.Validation and System.Diagnostics to your using list):

catch (DbEntityValidationException dbEx)
{
    foreach (var validationErrors in dbEx.EntityValidationErrors)
    {
        foreach (var validationError in validationErrors.ValidationErrors)
        {
            Trace.TraceInformation("Property: {0} Error: {1}", 
                                    validationError.PropertyName, 
                                    validationError.ErrorMessage);
        }
    }
}

No code change required:

While you are in debug mode within the catch {...} block open up the "QuickWatch" window (Ctrl+Alt+Q) and paste in there:

((System.Data.Entity.Validation.DbEntityValidationException)ex).EntityValidationErrors

or:

((System.Data.Entity.Validation.DbEntityValidationException)$exception).EntityValidationErrors

If you are not in a try/catch or don't have access to the exception object.

This will allow you to drill down into the ValidationErrors tree. It's the easiest way I've found to get instant insight into these errors.

In the case you have classes with same property names, here is a small extension to Praveen's answer:

 catch (DbEntityValidationException dbEx)
 {
    foreach (var validationErrors in dbEx.EntityValidationErrors)
    {
       foreach (var validationError in validationErrors.ValidationErrors)
       {
          Trace.TraceInformation(
                "Class: {0}, Property: {1}, Error: {2}",
                validationErrors.Entry.Entity.GetType().FullName,
                validationError.PropertyName,
                validationError.ErrorMessage);
       }
    }
 }

As an improvement to both Praveen and Tony, I use an override:

public partial class MyDatabaseEntities : DbContext
{
    public override int SaveChanges()
    {
        try
        {
            return base.SaveChanges();
        }
        catch (DbEntityValidationException dbEx)
        {
            foreach (var validationErrors in dbEx.EntityValidationErrors)
            {
                foreach (var validationError in validationErrors.ValidationErrors)
                {
                    Trace.TraceInformation("Class: {0}, Property: {1}, Error: {2}",
                        validationErrors.Entry.Entity.GetType().FullName,
                        validationError.PropertyName,
                        validationError.ErrorMessage);
                }
            }

            throw;  // You can also choose to handle the exception here...
        }
    }
}

This implementation wrap entity exception to exception with detail text. It handles DbEntityValidationException, DbUpdateException, datetime2 range errors (MS SQL), and include key of invalid entity in message (useful when savind many entities at one SaveChanges call).

First, override SaveChanges in DbContext class:

public class AppDbContext : DbContext
{
    public override int SaveChanges()
    {
        try
        {
            return base.SaveChanges();
        }
        catch (DbEntityValidationException dbEntityValidationException)
        {
            throw ExceptionHelper.CreateFromEntityValidation(dbEntityValidationException);
        }
        catch (DbUpdateException dbUpdateException)
        {
            throw ExceptionHelper.CreateFromDbUpdateException(dbUpdateException);
        }
    }   

    public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken)
    {
        try
        {
            return await base.SaveChangesAsync(cancellationToken);
        }
        catch (DbEntityValidationException dbEntityValidationException)
        {
            throw ExceptionHelper.CreateFromEntityValidation(dbEntityValidationException);
        }
        catch (DbUpdateException dbUpdateException)
        {
            throw ExceptionHelper.CreateFromDbUpdateException(dbUpdateException);
        }
    }

ExceptionHelper class:

public class ExceptionHelper
{
    public static Exception CreateFromEntityValidation(DbEntityValidationException ex)
    {
        return new Exception(GetDbEntityValidationMessage(ex), ex);
    }

    public static string GetDbEntityValidationMessage(DbEntityValidationException ex)
    {
        // Retrieve the error messages as a list of strings.
        var errorMessages = ex.EntityValidationErrors
            .SelectMany(x => x.ValidationErrors)
            .Select(x => x.ErrorMessage);

        // Join the list to a single string.
        var fullErrorMessage = string.Join("; ", errorMessages);

        // Combine the original exception message with the new one.
        var exceptionMessage = string.Concat(ex.Message, " The validation errors are: ", fullErrorMessage);
        return exceptionMessage;
    }

    public static IEnumerable<Exception> GetInners(Exception ex)
    {
        for (Exception e = ex; e != null; e = e.InnerException)
            yield return e;
    }

    public static Exception CreateFromDbUpdateException(DbUpdateException dbUpdateException)
    {
        var inner = GetInners(dbUpdateException).Last();
        string message = "";
        int i = 1;
        foreach (var entry in dbUpdateException.Entries)
        {
            var entry1 = entry;
            var obj = entry1.CurrentValues.ToObject();
            var type = obj.GetType();
            var propertyNames = entry1.CurrentValues.PropertyNames.Where(x => inner.Message.Contains(x)).ToList();
            // check MS SQL datetime2 error
            if (inner.Message.Contains("datetime2"))
            {
                var propertyNames2 = from x in type.GetProperties()
                                        where x.PropertyType == typeof(DateTime) ||
                                            x.PropertyType == typeof(DateTime?)
                                        select x.Name;
                propertyNames.AddRange(propertyNames2);
            }

            message += "Entry " + i++ + " " + type.Name + ": " + string.Join("; ", propertyNames.Select(x =>
                string.Format("'{0}' = '{1}'", x, entry1.CurrentValues[x])));
        }
        return new Exception(message, dbUpdateException);
    }
}

This code helped find my problem when I had issue with my Entity VAlidation Erros. It told me the exact problem with my Entity Definition. Try following code where you need to cover storeDB.SaveChanges(); in following try catch block.

  try
{
         if (TryUpdateModel(theEvent))
         {
             storeDB.SaveChanges();
             return RedirectToAction("Index");
         }
}
catch (System.Data.Entity.Validation.DbEntityValidationException dbEx)
{
    Exception raise = dbEx;
    foreach (var validationErrors in dbEx.EntityValidationErrors)
    {
        foreach (var validationError in validationErrors.ValidationErrors)
        {
            string message = string.Format("{0}:{1}", 
                validationErrors.Entry.Entity.ToString(),
                validationError.ErrorMessage);
            // raise a new exception nesting
            // the current instance as InnerException
            raise = new InvalidOperationException(message, raise);
        }
    }
    throw raise;
}

I was getting this error today and couldn't work it out for a while, but I realised it was after adding some RequireAttributes to my models and that some development seed data was not populating all of the required fields.
So just a note that if you're getting this error whilst updating the database through some sort of init strategy like DropCreateDatabaseIfModelChanges then you have to make sure that your seed data fulfils and satisfies any model data validation attributes.

I know this is slightly different to the problem in the question, but it's a popular question so I thought I'd add a bit more to the answer for others having the same issue as myself. Hope this helps others :)

I think adding try/catch for every SaveChanges() operation is not a good practice, it's better to centralize this :

Add this class to the main DbContext class :

public override int SaveChanges()
{
    try
    {
        return base.SaveChanges();
    }
    catch (DbEntityValidationException ex)
    {
        string errorMessages = string.Join("; ", ex.EntityValidationErrors.SelectMany(x => x.ValidationErrors).Select(x => x.ErrorMessage));
        throw new DbEntityValidationException(errorMessages);
    }
}

This will overwrite your context's SaveChanges() method and you'll get a comma separated list containing all the entity validation errors.

this also can improved, to log errors in production env, instead of just throwing an error.

hope this is helpful.

Here's an extension to Tony's extension... :-)

For Entity Framework 4.x, if you want to get the name and value of the key field so that you know which entity instance (DB record) has the problem, you can add the following. This provides access to the more powerful ObjectContext class members from your DbContext object.

// Get the key field name & value.
// This assumes your DbContext object is "_context", and that it is a single part key.
var e = ((IObjectContextAdapter)_context).ObjectContext.ObjectStateManager.GetObjectStateEntry(validationErrors.Entry.Entity);
string key = e.EntityKey.EntityKeyValues[0].Key;
string val = e.EntityKey.EntityKeyValues[0].Value;

I dont like exceptions I registered the OnSaveChanges and have this

var validationErrors = model.GetValidationErrors();

var h = validationErrors.SelectMany(x => x.ValidationErrors
                                          .Select(f => "Entity: " 
                                                      +(x.Entry.Entity) 
                                                      + " : " + f.PropertyName 
                                                      + "->" + f.ErrorMessage));

This error also happens when you try to save an entity that has validation errors. A good way to cause this is to forget to check ModelState.IsValid before saving to your DB.

Make sure that if you have nvarchar(50)in DB row you don't trying to insert more than 50characters in it. Stupid mistake but took me 3 hours to figure it out.

Thnaks for your answers, it help me alot. as i code in Vb.Net, this Bolt code for Vb.Net

Try
   Return MyBase.SaveChanges()
Catch dbEx As Validation.DbEntityValidationException
   For Each [error] In From validationErrors In dbEx.EntityValidationErrors
                       From validationError In validationErrors.ValidationErrors
                       Select New With { .PropertyName = validationError.PropertyName,
                                         .ErrorMessage = validationError.ErrorMessage,
                                         .ClassFullName = validationErrors.Entry.Entity
                                                                    .GetType().FullName}

        Diagnostics.Trace.TraceInformation("Class: {0}, Property: {1}, Error: {2}",
                                           [error].ClassFullName,
                                           [error].PropertyName,
                                           [error].ErrorMessage)
   Next
   Throw
End Try

it may caused by Property which is not populated by model.. instead it is populated by Controller.. which may cause this error.. solution to this is assign the property before applying ModelState validation. and this second Assumption is . you may have already have Data in your Database and trying to update it it but now fetching it.

This might be due to the maximum number of characters allowed for a specific column, like in sql one field might have following Data Type nvarchar(5) but the number of characters entered from the user is more than the specified, hence the error arises.

I have faced same issue a couple of days ago while updating the database. In my case, there was few new non nullable columns added for maintenance which was not supplied in the code which is causing the exception. I figure out those fields and supplied values for them and its resolved.

In my case I have a Table Column name Path which datatype i set was varchar(200).After updating it to nvarchar(max), I have deleted the table from edmx and then again added the table and it wokred properly for me.