Twitter'da paylaşım yaparken alınan hata

/share?url=http://www.domainname.com/link&text=olpa%E7ino--Bomba%20-%20 Invalid Unicode value in one or more parameters

 public static string ReplaceTwitterKarakter(string deger)
    { 
        
        deger = deger.Replace("ç","%C3%A7");
        deger = deger.Replace("ç","%C3%A7");
        deger = deger.Replace("Ç","%C3%87");
        deger = deger.Replace("ğ","%C4%9F");
        deger = deger.Replace("Ğ","%C4%9E");
        deger = deger.Replace("ı","%C4%B1");      
        deger = deger.Replace("I","%C4%B0");
        deger = deger.Replace("ö","%C3%B6");
        deger = deger.Replace("Ö","%C3%96");
        deger = deger.Replace("ş","%C5%9F");
        deger = deger.Replace("Ş","%C5%9E");
        deger = deger.Replace("ü","%C3%BC");
        deger = deger.Replace("Ü","%C3%9C");
        deger = deger.Replace(" ", "-");
        deger = deger.Replace(":", "-");
        return deger;
    }