<DataGrid>
    <DataGrid.RowStyle>
        <Style TargetType="DataGridRow">
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsError, Mode=OneWay}" Value="True">
                    <Setter Property="Foreground" Value="IndianRed"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </DataGrid.RowStyle>
</DataGrid>