Adding feed that requires Authentication returns NSXMLParserErrorDomain error 4.

[jimmywim]

MacOSX 10.8.2

Attempting to add an RSS feed that requires a username and password yields this error:

The feed URL you entered appears to be invalid.

Error Domain=MWFeedParser Code=3 "The operation couldn’t be completed. (NSXMLParserErrorDomain error 4.)" UserInfo=0x7ff5794fac70 {NSLocalizedDescription=The operation couldn’t be completed. (NSXMLParserErrorDomain error 4.)}

Output response from Charles when hitting Ok...

HTTP/1.1 403 Forbidden Cache-Control: private Content-Type: text/plain; charset=utf-8 Server: Microsoft-IIS/7.5 X-SharePointHealthScore: 6 X-Forms_Based_Auth_Required: https://XXXXXXXXXX.sharepoint.emea.microsoftonline.com/_forms/default.aspx?ReturnUrl=/_layouts/15/error.aspx&Source=%2f_layouts%2f15%2flistfeed.aspx%3fList%3d%257B845B9DC1-8C5D-429D-BE9E-2EA7A471B6EF%257D X-Forms_Based_Auth_Return_Url: https://XXXXXXXX.sharepoint.emea.microsoftonline.com/_layouts/15/error.aspx X-MSDAVEXT_Error: 917656; Access denied. Before opening files in this location, you must first browse to the web site and select the option to login automatically. X-AspNet-Version: 4.0.30319 SPRequestGuid: 84f83f9c-4d2b-d08a-8788-c0344bac71e8 request-id: 84f83f9c-4d2b-d08a-8788-c0344bac71e8 X-FRAME-OPTIONS: SAMEORIGIN SPRequestDuration: 120 SPIisLatency: 3186 X-Powered-By: ASP.NET MicrosoftSharePointTeamServices: 16.0.0.1922 X-Content-Type-Options: nosniff X-MS-InvokeApp: 1; RequireReadOnly P3P: CP="ALL IND DSP COR ADM CONo CUR CUSo IVAo IVDo PSA PSD TAI TELo OUR SAMo CNT COM INT NAV ONL PHY PRE PUR UNI" Date: Thu, 05 Sep 2013 09:02:05 GMT Content-Length: 13

403 FORBIDDEN

Update: This only appears to happen on Microsoft Office 365-hosted SharePoint sites, it works fine on an NTLM-protected self-hosted SharePoint site (it prompts for credentials).