Getting back the error message when uploading large files. (#9469)

* Attempt at fixing.
* Error message update.

Author: agr

src/NuGetGallery/Scripts/gallery/async-file-upload.js

@@ -193,8 +193,8 @@
                     break;
                 case "error":
                     // IIS returns 404.13 (NotFound) when maxAllowedContentLength limit is exceeded.
-                    if (fullResponse === "Not Found") {
-                        displayErrors(["The package file exceeds the size limit. Please try again."]);
+                    if (fullResponse === "Not Found" || fullResponse === "Request Entity Too Large") {
+                        displayErrors(["The package file exceeds the size limit of 250 MB. Please reduce the package size and try again."]);
                     }
                     else {
                         displayErrors(model.responseJSON);