# System.Web

``` diff
 namespace System.Web {
     public sealed class HttpUtility {
-        [return: NotNullIfNotNullAttribute("str")]
-        public static string UrlEncodeUnicode(string str);
+        [ObsoleteAttribute("This method produces non-standards-compliant output and has interoperability issues. The preferred alternative is UrlEncode(String).")]
+        [return: NotNullIfNotNullAttribute("str")]
+        public static string UrlEncodeUnicode(string str);
-        [return: NotNullIfNotNullAttribute("str")]
-        public static byte[] UrlEncodeUnicodeToBytes(string str);
+        [ObsoleteAttribute("This method produces non-standards-compliant output and has interoperability issues. The preferred alternative is UrlEncodeToBytes(String).")]
+        [return: NotNullIfNotNullAttribute("str")]
+        public static byte[] UrlEncodeUnicodeToBytes(string str);
     }
 }
```

