Skype mobile device sign in error: kCFErrorDomainCFNEtwork Code = 0x2 The operation couldn’t be completed

Recently, whilst setting up a Skype for Business proof of concept environment, I ran into an issue where desktop clients could sign in to Skype for Business, but mobile devices could not.


The first step is to confirm that external access has been configured correctly. If you haven’t ever used Microsoft’s free Lync connectivity Analyzer Tool, I highly suggest you give it a go.

Inputting my test user’s details, the connectivity analyzer returned a positive result.

I confirmed this using Microsoft’s other fantastic tool: which also reported that everything was ok.

The next step is to take a look at the logs on the mobile device. Spinning up Skype for Business, I turned on logging and then attempted to sign in to generate the logs.

Opening the logs in CMTrace (which is far far easier than reading them in Notepad), I could see many errors relating to the client receiving an invalid response from the server.

One such error was:

2018-02-12 00:32:28.905 SfB[688:16ea7b000] ERROR TRANSPORT CHttpConnection.cpp/1026:Request Type = UcwaAutoDiscoveryRequest Error domain = kCFErrorDomainCFNetwork code = 0x2 ErrorDescription = The operation couldn…….t be completed. (kCFErrorDomainCFNetwork error 2.) ErrorFailureReason =  ErrorRecoverySuggestion =

The logs seemed to suggest that the client was receiving invalid information from the server, and therefore was unable to authenticate.


During the PoC deployment, Windows 2012 r2 had been deployed as the base image for all Skype for Business server roles.  IS Application Request Routing version 2.5 had been installed and configured for use as the reverse proxy.

IIS 2.5 isnt supported on Windows 2012 r2, and will generate some pretty funky errors. The solution is to simply remove IIS ARR 2.5, along with any ARR patches and install IIS ARR 3.0.

Once ARR 3.0 has been installed, and the server farms removed and re-created users were then able to sign in from mobile devices.

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