Validation failed for one or more entities. See 'EntityValidationErrors' property for more details [duplicate]

Answer 1

Was also struggling with this error and based on the topic here and this answer was able to figure out snippet to copy/paste without the need to figure out what has to be imported (excellent for C# beginners), code below:

try
{
  context.SaveChanges();
}
catch (System.Data.Entity.Validation.DbEntityValidationException ex)
{
  foreach (var entityValidationErrors in ex.EntityValidationErrors)
  {
    foreach (var validationError in entityValidationErrors.ValidationErrors)
    {
      System.Diagnostics.Debug.WriteLine("Property: " + validationError.PropertyName + " Error: " + validationError.ErrorMessage);
    }
  }
}

Answer 2

If you're using IIS with Windows Authentification and Entity Framework, be careful to use authorize.

I tried to POST without authorize and it didn't work, and get this error on db.SaveChangesAsync();, while all other verbs GET and DELETE were working.

But when I added AuthorizeAttribute as annotation, it worked.

[Authorize]
public async Task<IHttpActionResult> Post(...){
....
}

Answer 3

just Check Your Database Table Field Length . Your Input Text Is Greater than the length of column field data type length

Answer 4

Please check the fields value you are passing, are valid and according to database fields. For example number of characters passed in a particular field are less than the characters defined in database table field.

Answer 5

Just throwing my two cents in...

Within my dbConfiguration.cs, I like to wrap my context.SaveChanges() method into a try/catch and produce an output text file that allows me to read the Error(s) clearly, and this code also timestamps them - handy if you run into more than one error at different times!

        try
        {
            context.SaveChanges();
        }
        catch (DbEntityValidationException e)
        {
            //Create empty list to capture Validation error(s)
            var outputLines = new List<string>();

            foreach (var eve in e.EntityValidationErrors)
            {
                outputLines.Add(
                    $"{DateTime.Now}: Entity of type \"{eve.Entry.Entity.GetType().Name}\" in state \"{eve.Entry.State}\" has the following validation errors:");
                outputLines.AddRange(eve.ValidationErrors.Select(ve =>
                    $"- Property: \"{ve.PropertyName}\", Error: \"{ve.ErrorMessage}\""));
            }
            //Write to external file
            File.AppendAllLines(@"c:\temp\dbErrors.txt", outputLines);
            throw;
        }

Answer 6

If you are simply catching a generic exception, it may benefit you to cast this as a DbEntityValidationException. This type of an exception has a Validation Errors property, and continuing to expand your way into them, you will find all the problems.

For example, if you put a break point in the catch, you can throw the following into a watch:

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

An example of an error is if a field does not allow nulls, and you have a null string, you'll see it say that the field is required.