I've decompiled a .net exe using dotpeek and justdecompile and I am getting a lot of errors about the namespace prefix "0" is not defined  when imported into Visual Studio. The errors are coming from XAML files

Content="{Binding Path=Double, StringFormat={0:c}}"/>
Binding="{Binding Path=DateTime_payment, StringFormat='{0:MMM-dd-yyyy hh:mm tt}'}"/>
Binding="{Binding Path=Payment_total_amount, StringFormat='{0:$#,##0.00}'}"/>            

Above is an example of where i am getting the errors. This exe uses US locale and all I want to do is change it to uk. This is the only reason I decompiled it as I dont have source code.   

Sounds like you are missing some required xmlns' at the top of the file to tell it what is looking to follow standards wise. 

Things like this:

             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:ignore="http://www.ignore.com"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             mc:Ignorable="d ignore" 

 

I have these at the top

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:Saloon"
        xmlns:db="clr-namespace:SaloonDB;assembly=SaloonDB"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"

 

You can't use StringFormat in "Content" property ,instead try to use ContentStringFormat

https://msdn.microsoft.com/en-us/library/system.windows.controls.contentcontrol.contentstringformat(v=vs.110).aspx

Good luck.