Entity Framework Core: `SqlNullValueException: Data is Null.` How to troubleshoot?

c# asp.net-core .net-core entity-framework-core
83,847

Solution 1

The error message indicates that EF Core is trying to read string value for a required property, i.e. a property which should never have null value in the database, but instead the underlying data reader reports null value for that property in some record(s).

Looking at your entity model and corresponding database table, you can see the obvious discrepancy for many string properties -> varchar columns. CompanyStreetAddress, CompanyCity, CompanyZipCode, CompanyVatNumber, ContactFirstName, ContactLastName - all these are marked as [Required] in the model, bit have no corresponding not null constraint in the table.

So the problem is caused by one or more of these columns.

You need to fix that discrepancy - probably by removing [Required] attribute because the constraint is already broken in the existing data.

The fact that it "works" in some older EF Core version doesn't matter - that's incorrect mapping and as such should be fixed. Technically it shouldn't worked from the beginning. But remember that EF Core is still in active development and has many bugs which are fixed in the next release(s). Most likely some code change was made between "working" and "non working" EF Core version which fixes the previous incorrect behavior.

Solution 2

If you are trying to read some nullable data from the database, but your type is not nullable you can get this error.

If MyInt is nullable in the database and you have this entity:

public class MyEntity
{
    public int Id { get; set; }
    public int MyInt { get; set; }
}

You will get the exception: System.Data.SqlTypes.SqlNullValueException: 'Data is Null. This method or property cannot be called on Null values.'

To fix this, just change the type of your MyInt property to Nullable<int> or int?:

public class MyEntity
{
    public int Id { get; set; }
    public int? MyInt { get; set; }
}

Note: This is not an answer to the original question, but is an answer to the question in the title.

Solution 3

This kind of exception can also appear if you enable latest Nullable feature from C# 8.

EF Core, at least currently, it's not fully compatible with C# 8 nullable types. So for example, given that you enable the Nullable feature for the project, if you have a type like this:

public class MyEntity
{
   public string MyProperty { get; set; }
}

even if the property it's not marked with the [Required] attribute, EF core raise this kind of exception because it requires that value in database it's not null (i.e. it doesn't test the column value with IsDbNull).

For further info on how to handle nullable reference types in EF core take a look at: https://docs.microsoft.com/en-us/ef/core/miscellaneous/nullable-reference-types

Solution 4

To fix similar issue with Data is Null exception, I had to explicitly put IsRequired(false) on my column mapping. In my case I was mapping a database view.

builder.Property(x => x.MyProperty).IsRequired(false);

Solution 5

SOLUTION: Yes, the error "SqlNullValueException: Data is Null." is caused when a column (of a table) contains NULL when the model has marked the field causing the problem as [Required]... the problem is resolved easily with numeric fields but is really bad when the field is of type string...

Think about the following 2 classes that use the example of a distribution route, each route has a driver, and of course, each driver then has 1 or more routes.

public class Route
    {
        public int id { get; set; }       
        public string RouteName { get; set; }

        [Required] \\==> FIELD CAUSING THE PROBLEM
        public string UsuarioId { get; set; }

        public virtual Usuario Driver { get; set; }
}

public class Usuario
    {
        public string Id {get;set;
        public string Name { get; set; }                
        public virtual List<Route> Routes { get; set; } = new List<Route>();

    }

As you may guess, a Route can have a single driver (or Usuario as I have called it), but a Driver can have multiple routes, this makes a one-to-many relationship as follow:

protected override void OnModelCreating(ModelBuilder modelBuilder){            

     base.OnModelCreating(modelBuilder);

     modelBuilder.Entity<Usuario>()
        .HasMany<Route>(usuario => usuario.Routes)
        .WithOne(route => route.Driver)
        .HasForeignKey(route => route.UsuarioId)
        .OnDelete(DeleteBehavior.SetNull);
                
}

According to the FluentAPI, when a driver is deleted the behavior is to set the UsuarioId field (in Routes model) to NULL, but this violates the [Required] attribute. So we will not be able to delete a record in the Users (or Drivers) table. Also, if we have data already in the database, in this case, Routes with NULL UsuarioId, it will present the error immediatly.

Remember, the point is: We want the [Required] to be used only for validation purposes, as we could have Routes that have not been assigned to a Driver (UserId) yet, so in the database, it should be allowed to be NULL, not in our mvc forms.

To resolve the issue, mark the field as [required], then go to the DbContext class where you did define the relationships using fluent API, and do specify that the column is not required like this:

modelBuilder.Entity<Route>()
   .Property(p => p.UsuarioId).IsRequired(required: false);

so the field is now required under the annotation schema but not required by the fluent API which will be ultimately used to build the database. This will resolve the problem!

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83,847
Natalie Perret
Author by

Natalie Perret

🐈Meow.

Updated on July 05, 2022

Comments

  • Natalie Perret
    Natalie Perret almost 2 years

    I am using Entity Framework Core in an ASP.NET Core application and Controller action and I haven't changed something to the working code nor to the database but I can't tell what is the query performed by Entity Framework Core.

    The controller action:

    [HttpGet]
// GET: Administration/Companies
public async Task<ActionResult> Index()
{
    var users = await UserManager.Users.ToListAsync();

    var companyEditVMs = await DB.Companies
    .OrderBy(company => company.CompanyId == 1 
        ? "_" + company.CompanyName 
        : company.CompanyName
    )
    Select(a => new CompanyEditVM(HttpContext, a, users.Where(b => b.CompanyId == a.CompanyId)))
    .ToListAsync();

    return View(companyEditVMs);
}

    The trace

    SqlNullValueException: Data is Null. This method or property cannot be called on Null values.
System.Data.SqlClient.SqlBuffer.get_String()
System.Data.SqlClient.SqlDataReader.GetString(int i)
lambda_method(Closure , DbDataReader )
Microsoft.EntityFrameworkCore.Storage.Internal.TypedRelationalValueBufferFactory.Create(DbDataReader dataReader)
Microsoft.EntityFrameworkCore.Query.Internal.AsyncQueryingEnumerable<T>+AsyncEnumerator.BufferlessMoveNext(DbContext _, bool buffer, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync<TState, TResult>(TState state, Func<DbContext, TState, CancellationToken, Task<TResult>> operation, Func<DbContext, TState, CancellationToken, Task<ExecutionResult<TResult>>> verifySucceeded, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Query.Internal.AsyncQueryingEnumerable<T>+AsyncEnumerator.MoveNext(CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider+ExceptionInterceptor<T>+EnumeratorExceptionInterceptor.MoveNext(CancellationToken cancellationToken)
System.Linq.AsyncEnumerable.Aggregate_<TSource, TAccumulate, TResult>(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> accumulator, Func<TAccumulate, TResult> resultSelector, CancellationToken cancellationToken) in Aggregate.cs
KYC.Core.Areas.Commercial.Controllers.CompaniesController.Index() in CompaniesController.cs
-
        [HttpGet]
        // GET: Administration/Companies
        public async Task<ActionResult> Index()
        {
            var users = await UserManager.Users.ToListAsync();

            var companyEditVMs = await DB.Companies
                .OrderBy(company => company.CompanyId == 1 
                    ? "_" + company.CompanyName 
                    : company.CompanyName
                )
                .Select(a => new CompanyEditVM(HttpContext, a, users.Where(b => b.CompanyId == a.CompanyId)))
                .ToListAsync();
lambda_method(Closure , object )
Microsoft.Extensions.Internal.ObjectMethodExecutorAwaitable+Awaiter.GetResult()
Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor+TaskOfActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, object controller, object[] arguments)
System.Threading.Tasks.ValueTask<TResult>.get_Result()

    I even tried to do just var companies = await DB.Companies.ToListAsync(). and I have exactly the same exception.

    Maybe I would like to be able to fetch the query performed by EF Core to do that manually so that I can try to figure out what's wrong with the query.

    I am wondering what possibly could have happened. Especially since other entities like user or countries can still be fetched from the database.

    Any idea how can I troubleshoot the actual underlying issue?

    [EDIT]

    The only that actually changed in the "code" are the nuget references, I basically upgraded pretty much everything although it didn't break a reference in the code it seems it change how EF Core is somehow (wild guess) interpreting the database.

    I did reset my git repository to the point just before the nuget packages update happened and things work.,. I then decided to just update EntityFrameworkCore from 2.0.2 to 2.2.4 (also tried with 2.2.0 and ended up with the same result) and the issue happens again... Not sure what have changed between 2.0.2 and 2.2.0 to trigger this exception (but the model is the same just the EF Core version changed)...

    Here is the entity definition, it seems to have been auto-generated with a tool from the database table / schema:

    
    [Table("T_Companies")]
    public partial class Company : INotifyPropertyChanging, INotifyPropertyChanged
    {
        public override string ToString()
        {
            return CompanyId + " " + CompanyName;
        }

        private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(string.Empty);

        private int _CompanyId;

        private string _CompanyName;

        private int _CompanyTypeId;

        private int _CountryId;

        private string _CompanyVatNumber;

        private string _CompanyStreetAddress;

        private string _CompanyZipCode;

        private string _CompanyCity;

        private string _ContactLastName;

        private string _ContactFirstName;

        private bool? _Active;

        private int? _AccountId;

        private string _CallbackSalt;

        private int? _UserSpaceId;

        private string _Login;

        private string _Pwd;

        private bool _IsTechnicalAccount;

        private DateTime? _StatusDate;

        private int _BankStatusCode;

        private string _PivotalAccount;

        private CompanyType _CompanyType;

        private Country _Country;

        private bool _IsKycIdSent;

        #region Extensibility Method Definitions
        partial void OnLoaded();
        partial void OnCreated();
        partial void OnCompanyIdChanging(int value);
        partial void OnCompanyIdChanged();
        partial void OnCompanyNameChanging(string value);
        partial void OnCompanyNameChanged();

        partial void OnCompanyCityChanging(string value);
        partial void OnCompanyCityChanged();
        partial void OnCompanyZipCodeChanging(string value);
        partial void OnCompanyZipCodeChanged();
        partial void OnContactLastNameChanging(string value);
        partial void OnContactLastNameChanged();
        partial void OnActiveChanging(bool? value);
        partial void OnActiveChanged();
        partial void OnCompanyTypeIdChanging(int value);
        partial void OnCompanyTypeIdChanged();
        partial void OnCountryIdChanging(int value);
        partial void OnCountryIdChanged();
        partial void OnContactFirstNameChanging(string value);
        partial void OnContactFirstNameChanged();
        partial void OnCompanyVatNumberChanging(string value);
        partial void OnCompanyVatNumberChanged();
        partial void OnCompanyStreetAddressChanged();
        partial void OnCompanyStreetAddressChanging(string value);
        partial void OnAccountIdChanging(int? value);
        partial void OnAccountIdChanged();
        partial void OnCallbackSaltChanging(string value);
        partial void OnCallbackSaltChanged();
        partial void OnUserSpaceIdChanging(int? value);
        partial void OnUserSpaceIdChanged();
        partial void OnLoginChanging(string value);
        partial void OnLoginChanged();
        partial void OnPwdChanging(string value);
        partial void OnPwdChanged();
        partial void OnIsTechnicalAccountChanging(bool value);
        partial void OnIsTechnicalAccountChanged();
        partial void OnStatusDateChanging(DateTime? value);
        partial void OnStatusDateChanged();
        partial void OnBankStatusCodeChanging(int value);
        partial void OnBankStatusCodeChanged();
        partial void OnPivotalAccountChanging(string value);
        partial void OnPivotalAccountChanged();
        partial void OnIsKycIdSentChanging(bool value);
        partial void OnIsKycIdSentChanged();

        #endregion

        public Company()
        {
            OnCreated();
        }

        [Key, Column("CompanyId"), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int CompanyId
        {
            get => _CompanyId;
            set
            {
                if (_CompanyId != value)
                {
                    OnCompanyIdChanging(value);
                    SendPropertyChanging();
                    _CompanyId = value;
                    SendPropertyChanged("CompanyId");
                    OnCompanyIdChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(1024), Column("CompanyName"), Required]
        public string CompanyName
        {
            get => _CompanyName;
            set
            {
                if (_CompanyName != value)
                {
                    OnCompanyNameChanging(value);
                    SendPropertyChanging();
                    _CompanyName = value;
                    SendPropertyChanged("CompanyName");
                    OnCompanyNameChanged();
                }
            }
        }

        [Column("CompanyTypeId"), Required]
        public int CompanyTypeId
        {
            get => _CompanyTypeId;
            set
            {
                if (_CompanyTypeId != value)
                {
                    OnCompanyTypeIdChanging(value);
                    SendPropertyChanging();
                    _CompanyTypeId = value;
                    SendPropertyChanged("CompanyTypeId");
                    OnCompanyTypeIdChanged();
                }
            }
        }


        [Column("CountryId"), Required]
        public int CountryId
        {
            get => _CountryId;
            set
            {
                if (CountryId != value)
                {
                    OnCountryIdChanging(value);
                    SendPropertyChanging();
                    _CountryId = value;
                    SendPropertyChanged("CountryId");
                    OnCountryIdChanged();
                }
            }
        }


        [DataType(DataType.Text), StringLength(100), Column("CompanyCity"), Required]
        public string CompanyCity
        {
            get => _CompanyCity;
            set
            {
                if (_CompanyCity != value)
                {
                    OnCompanyCityChanging(value);
                    SendPropertyChanging();
                    _CompanyCity = value;
                    SendPropertyChanged("CompanyCity");
                    OnCompanyCityChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(100), Column("CompanyStreetAddress"), Required]
        public string CompanyStreetAddress
        {
            get => _CompanyStreetAddress;
            set
            {
                if (_CompanyStreetAddress != value)
                {
                    OnCompanyStreetAddressChanging(value);
                    SendPropertyChanging();
                    _CompanyStreetAddress = value;
                    SendPropertyChanged("CompanyStreetAddress");
                    OnCompanyStreetAddressChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(30), Column("CompanyVatNumber"), Required]
        public string CompanyVatNumber
        {
            get => _CompanyVatNumber;
            set
            {
                if (_CompanyVatNumber != value)
                {
                    OnCompanyVatNumberChanging(value);
                    SendPropertyChanging();
                    _CompanyVatNumber = value;
                    SendPropertyChanged("CompanyVatNumber");
                    OnCompanyVatNumberChanged();
                }
            }
        }


        [DataType(DataType.Text), StringLength(10), Column("CompanyZipCode"), Required]
        public string CompanyZipCode
        {
            get => _CompanyZipCode;
            set
            {
                if (_CompanyZipCode != value)
                {
                    OnCompanyZipCodeChanging(value);
                    SendPropertyChanging();
                    _CompanyZipCode = value;
                    SendPropertyChanged("CompanyZipCode");
                    OnCompanyZipCodeChanged();
                }
            }
        }


        [DataType(DataType.Text), StringLength(1024), Column("ContactLastName"), Required]
        public string ContactLastName
        {
            get => _ContactLastName;
            set
            {
                if (_ContactLastName != value)
                {
                    OnContactLastNameChanging(value);
                    SendPropertyChanging();
                    _ContactLastName = value;
                    SendPropertyChanged("ContactLastName");
                    OnContactLastNameChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(1024), Column("ContactFirstName"), Required]
        public string ContactFirstName
        {
            get => _ContactFirstName;
            set
            {
                if (_ContactFirstName != value)
                {
                    OnContactFirstNameChanging(value);
                    SendPropertyChanging();
                    _ContactFirstName = value;
                    SendPropertyChanged("ContactFirstName");
                    OnContactFirstNameChanged();
                }
            }
        }

        [Column("Active"), Required]
        public bool? Active
        {
            get => _Active;
            set
            {
                if (_Active != value)
                {
                    OnActiveChanging(value);
                    SendPropertyChanging();
                    _Active = value;
                    SendPropertyChanged("Active");
                    OnActiveChanged();
                }
            }
        }

        [Column("AccountId")]
        public int? AccountId
        {
            get => _AccountId;
            set
            {
                if (_AccountId != value)
                {
                    OnAccountIdChanging(value);
                    SendPropertyChanging();
                    _AccountId = value;
                    SendPropertyChanged("AccountId");
                    OnAccountIdChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(1024), Column("CallbackSalt")]
        public string CallbackSalt
        {
            get => _CallbackSalt;
            set
            {
                if (_CallbackSalt != value)
                {
                    OnCallbackSaltChanging(value);
                    SendPropertyChanging();
                    _CallbackSalt = value;
                    SendPropertyChanged("CallbackSalt");
                    OnCallbackSaltChanged();
                }
            }
        }

        [Column("UserSpaceId")]
        public int? UserSpaceId
        {
            get => _UserSpaceId;
            set
            {
                if (_UserSpaceId != value)
                {
                    OnUserSpaceIdChanging(value);
                    SendPropertyChanging();
                    _UserSpaceId = value;
                    SendPropertyChanged("UserSpaceId");
                    OnUserSpaceIdChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(1024), Column("Login")]
        public string Login
        {
            get => _Login;
            set
            {
                if (_Login != value)
                {
                    OnLoginChanging(value);
                    SendPropertyChanging();
                    _Login = value;
                    SendPropertyChanged("Login");
                    OnLoginChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(1024), Column("Pwd")]
        public string Pwd
        {
            get => _Pwd;
            set
            {
                if (_Pwd != value)
                {
                    OnPwdChanging(value);
                    SendPropertyChanging();
                    _Pwd = value;
                    SendPropertyChanged("Pwd");
                    OnPwdChanged();
                }
            }
        }

        [Column("IsTechnicalAccount"), Required]
        public bool IsTechnicalAccount
        {
            get => _IsTechnicalAccount;
            set
            {
                if (_IsTechnicalAccount != value)
                {
                    OnIsTechnicalAccountChanging(value);
                    SendPropertyChanging();
                    _IsTechnicalAccount = value;
                    SendPropertyChanged("IsTechnicalAccount");
                    OnIsTechnicalAccountChanged();
                }
            }
        }

        [DataType(DataType.DateTime), Column("StatusDate")]
        public DateTime? StatusDate
        {
            get => _StatusDate;
            set
            {
                if (_StatusDate != value)
                {
                    OnStatusDateChanging(value);
                    SendPropertyChanging();
                    _StatusDate = value;
                    SendPropertyChanged("StatusDate");
                    OnStatusDateChanged();
                }
            }
        }

        [Column("BankStatusCode")]
        public int BankStatusCode
        {
            get => _BankStatusCode;
            set
            {
                if (_BankStatusCode != value)
                {
                    OnBankStatusCodeChanging(value);
                    SendPropertyChanging();
                    _BankStatusCode = value;
                    SendPropertyChanged("BankStatusCode");
                    OnBankStatusCodeChanged();
                }
            }
        }

        [DataType(DataType.Text), StringLength(255), Column("PivotalAccount")]
        public string PivotalAccount
        {
            get => _PivotalAccount;
            set
            {
                if (_PivotalAccount != value)
                {
                    OnPivotalAccountChanging(value);
                    SendPropertyChanging();
                    _PivotalAccount = value;
                    SendPropertyChanged("PivotalAccount");
                    OnPivotalAccountChanged();
                }
            }
        }

        public List<Resultat> Resultats { get; set; }

        public CompanyType CompanyType
        {
            get => _CompanyType;
            set
            {
                var previousValue = _CompanyType;
                if (previousValue != value)
                {
                    SendPropertyChanging();
                    _CompanyType = value;
                    if (value != null)
                    {
                        CompanyTypeId = value.CompanyTypeId;
                    }
                    else
                    {
                        _CompanyTypeId = default;
                    }
                    SendPropertyChanged("CompanyType");
                }
            }
        }

        public Country Country
        {
            get => _Country;
            set
            {
                var previousValue = _Country;
                if (previousValue != value)
                {
                    SendPropertyChanging();
                    _Country = value;
                    _CountryId = value?.CountryId ?? default;
                    SendPropertyChanged("Country");
                }
            }
        }

        [Column("IsKycIdSent"), Required]
        public bool IsKycIdSent
        {
            get => _IsKycIdSent;
            set
            {
                if (_IsKycIdSent != value)
                {
                    OnIsKycIdSentChanging(value);
                    SendPropertyChanging();
                    _IsKycIdSent = value;
                    SendPropertyChanged("IsKycIdSent");
                    OnIsKycIdSentChanged();
                }
            }
        }

        public event PropertyChangingEventHandler PropertyChanging;

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void SendPropertyChanging()
        {
            PropertyChanging?.Invoke(this, emptyChangingEventArgs);
        }

        protected virtual void SendPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        private void Attach_Resultats(Resultat entity)
        {
            SendPropertyChanging();
            entity.Company = this;
        }

        private void Detach_Resultats(Resultat entity)
        {
            SendPropertyChanging();
            entity.Company = null;
        }
    }

    and the related table creation script:

    create table T_Companies
(
    CompanyId            int identity (10) identity
        primary key nonclustered,
    CompanyName          varchar(1024) not null,
    CompanyTypeId        int           not null
        constraint FK_Company_CompanyType
            references T_CompanyTypes,
    CountryId            int           not null
        constraint FK_Company_Country
            references T_Countries,
    Active               bit           not null,
    AccountId            int,
    CallbackSalt         varchar(1024),
    UserSpaceId          int,
    Login                varchar(1024),
    Pwd                  varchar(1024),
    StatusDate           datetime(23, 3),
    BankStatusCode       int           not null,
    PivotalAccount       varchar(255),
    IsTechnicalAccount   bit           not null,
    CompanyStreetAddress varchar(256),
    CompanyCity          varchar(256),
    CompanyZipCode       varchar(10),
    CompanyVatNumber     varchar(30),
    ContactFirstName     varchar(20),
    ContactLastName      varchar(20),
    IsKycIdSent          bit           not null
)
go

    [EDIT 2]

    For the very same model, this (in the project file the nuget references) works

    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.1.8" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.8" />

    while those ones, no:

    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.2.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.2.0" />

    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.2.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.8" />
  • Natalie Perret
    Natalie Perret about 5 years
    Thanks this was actually the underlying issue ~~ didn't know that EF Core used to be more "tolerant" buggyish in early stage to the point of letting go of some column constraints. Thanks for pointing this out.
  • Gert Arnold
    Gert Arnold over 4 years
    This doesn't seem to be related to the question at all. Also, if it does, how does this significantly add something to existing answers?
  • Hari Lakkakula
    Hari Lakkakula over 4 years
    Thank you @GertArnold ,while loads the data in Entity framework, it do mapping with model. if payload data is not match with data type it throws Exception. I have one case i have bit field in DB ,unfortunately it inserted null data. while loading the bit field Entity framework throws null ref exception , due to miss match of datatype and loaded datatype.
  • Gert Arnold
    Gert Arnold over 4 years
    Yes, and that was sufficiently explained by Ivan. Your answer doesn't add anything new. Also, it's not a null reference exception that is thrown.
  • Jogge
    Jogge almost 4 years
    Related question/answer: stackoverflow.com/q/62015584/7108481
  • Pascal R.
    Pascal R. over 3 years
    In short words: With C# 8, MyProperty needs to be string? if it is a nullable value in the database.
  • Natalie Perret
    Natalie Perret over 3 years
    Thanks for your answer, this is absolutely fantastic!
  • Dominic Shaw
    Dominic Shaw over 3 years
    Doing this revealed that because the column in question for me was part of a composite key, it was automatically marked required by EF, which led to the problem. This didn't solve the problem but it revealed it.TVM
  • Jota.Toledo
    Jota.Toledo over 3 years
    In my case, this error started to appear once I activated nullable reference types at project level, without making the necessary changes to my entity classes. Disabling the feature did the trick.
  • shinyshark
    shinyshark over 2 years
    Hello Asif, I had the same issue. In my situation it was better to change from 'int' to 'int?' to allow null. The corresponding column in the database allowed nulls as well. The reason it worked for you is because strings are always nullable.
  • Smile4ever
    Smile4ever about 2 years
    I had to change the type string into string?
  • Madhav Shenoy
    Madhav Shenoy about 2 years
    I spent 2 hours trying to figure out why EF was failing. Thanks,
  • DaveDev
    DaveDev almost 2 years
    I like your "Note:" - it's the difference between what the customer asked for and what they actually want.

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