Xaml Error: Severity Code Description Project File Line Suppression StateError

I have 4 error in my .Xaml coding

the below error message is coming in my coding

Severity Code Description Project File Line Suppression StateError The name "BooleanToFontWeightConverter" does not exist in the namespace "clr-namespace:Converters". PurgeALL D:\ram\Projects\Purge All\AutoCad Purge All -\PurgeALL - Copy\PurgeALL\Resources\Converters.xaml 5

the below bolded lines in my codings are error lines

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:converters="clr-namespace:Converters">

    <converters:BooleanToFontWeightConverter x:Key="BooleanToFontWeightConverter" />
    <converters:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
    <converters:ToUpperConverter x:Key="ToUpperConverter" />
    <converters:ToLowerConverter x:Key="ToLowerConverter" />
    
</ResourceDictionary>