System.TypeLoadException: Could not resolve type with token 01000035

I'm getting recently this error whenever I build my app.
Unhandled Exception:

System.TypeLoadException: Could not resolve type with token 01000035 (from typeref, class/assembly Xamarin.Forms.FontAttributesConverter, Xamarin.Forms.Core, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)

After some inspectations, I found out that this bug is caused from App.xaml, specifically this part of code:
`

        <Style x:Key="IB" TargetType="Label">
            <Setter Property="FontAttributes" Value="Bold, Italic" />
        </Style>
        <Color x:Key="P">#9e42f4</Color>
        <Color x:Key="P_Selected">#660bb9</Color>
        <OnPlatform x:TypeArguments="x:String" x:Key="MFont"
                    iOS="Oswald" Android="oswald-r.ttf#Oswald">
        </OnPlatform>
        <Style x:Key="Skip" TargetType="Button">
            <Setter Property="BackgroundColor" Value="Transparent"/>
            <Setter Property="TextColor" Value="White"/>
            <Setter Property="FontAttributes" Value="Bold"/>
            <Setter Property="FontSize" Value="19"/>
            <Setter Property="Margin" Value="20,20,20,20"/>
            <Setter Property="HorizontalOptions" Value="End"/>
            <Setter Property="FontFamily" Value="{StaticResource MFont}"/>
        </Style>

`
I have a custom font installed on both IOS and Android projects. Deleting bin and obj folders didn't fix the problem and strangely enough, this bug has never occured before I tested the app recently.