I have noticed DataGrid columns in my project do not stretch to DataGrid width any more. The only thing I did is changed Assmbly name. 
In XAML designer they are stretched. 

![Collapsed DataGrid Columns](https://i.stack.imgur.com/F11D4.jpg)

```
    <DataGrid  x:Name="dg" Grid.Row="4" RowHeaderWidth="0" AutoGenerateColumns="False" 
     HorizontalGridLinesBrush="AliceBlue" AlternationCount="2">                

                <DataGrid.Columns>
                    <DataGridTemplateColumn Header="File"  IsReadOnly="True" Width="*" CanUserSort="True" SortMemberPath="File" >
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <TextBlock  Text="{Binding Path=FileName}" MouseDown="FileName_MouseDown" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>

//other columns are similar

                </DataGrid.Columns>                
            </DataGrid>

```

What I have tried:

1. Rebuild solution
2. Delete "bin" folder and rebuild
3. I used old version which was OK, and changed Assembly name (which was only difference between backups) and I compared all files between these two versions (in codecompare and notepad++, one by one) and all files were the same but one stretches and the other doesn't. Both version too are old so I can not go back.
4. Create new Datagrid with just ColumnWidth="\*" AutogenerateColumns="True"
5. HorizontalContentAlignment="Stretch" and HorizontalAlignment="Stretch"

I ran of ideas. Please offer any idea no matter if silly. Thanks!