Hello Karl-Michael Beck, 

I have been looking into your issue and in order to test this out I whipped up a small test sample (Grid_IDataError_row_border.zip) where everything seems to work as expected with the UnboundFields. Please look into the attachment I have created for you  and let me know if there is anything I am missing, or if this solved you issue. 

Looking forward to hearing from you.

<Window x:Class="DataErrorInfoProblem2.MainWindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         Title="MainWindow" Height="350" Width="525" xmlns:igDP="http://infragistics.com/DataPresenter">     <Grid>         <StackPanel Orientation="Vertical">             <Button Click="Button_Click" >hit me</Button>             <igDP:XamDataGrid HorizontalAlignment="Left" Name="xamDataGrid1" RecordContainerGenerationMode="LazyLoad"  >                 <igDP:XamDataGrid.FieldLayoutSettings>                     <igDP:FieldLayoutSettings SupportDataErrorInfo="RecordsAndCells"/>                 </igDP:XamDataGrid.FieldLayoutSettings>             </igDP:XamDataGrid>         </StackPanel>     </Grid> </Window>

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MainWindow.cs:

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes;

namespace DataErrorInfoProblem2 {     /// <summary>     /// Interaktionslogik für MainWindow.xaml     /// </summary>     public partial class MainWindow : Window     {         public MainWindow()         {             InitializeComponent();             bool aShowProblem = true;                         this.xamDataGrid1.FieldLayoutSettings.AutoGenerateFields = !aShowProblem;             this.xamDataGrid1.DataSource = new CRecord[] { this.Record };         }

        private CRecord Record = new CRecord();

        private void Button_Click(object sender, RoutedEventArgs e)         {             if(this.Record.Error == string.Empty)             {                 this.Record.Error = "TestError";             }             else             {                 this.Record.Error = String.Empty;             }         }     }

    public class CRecord : System.ComponentModel.IDataErrorInfo, System.ComponentModel.INotifyPropertyChanged     {         public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;

        private string ErrorM = "TestError";         public string Error         {             set             {                 this.ErrorM = value;                 if (null != this.PropertyChanged)                 {                     this.PropertyChanged(this, new System.ComponentModel.PropertyChangedEventArgs(""));                 }             }             get             {                 return this.ErrorM;             }         }

        public string this[string aName]         {             get             {                 return string.Empty;             }         }     }

}