Event 18456 – Start-CsPool Error Failed to Connect to BackEnd

I hit an expected snag recently where I wasn’t able to get an existing SfB 2015 Front-End pool to start after growing it from 1 to 3 servers. Coincidentally I’d performed this same job for another customer maybe a month prior and it had gone off without a hitch. Not so this time.

Try as I might, no amount of resetting the fabric with Reset-CsPoolRegistrarState was going to work; the pool steadfastly refused to start:


Start-CsPool : Please make sure at least 2 machine<s> are in running or starting state to achieve fabric network ring quorum from the following machine list. Also makes sure Windows Fabric Host Service is running on those machines.

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SfB 2015 Server Update – March 2018

Our March 2018 update nudges the server up from 6.0.9319.510 to 6.0.9319.516 and updates 7 components on my Standard Edition Front-End. It doesn’t seem to be officially called CU7, but so far Martin and I are going with that. I’ll update the post if I’m advised to the contrary. CU6 HF2 it is, thanks Tim!

What’s Fixed?

According to the kb, “This update enables Location-Based Routing to support the Skype for Business mobile clients”, but the last one said that too.

It also fixes the following issues:

  • Kb4036626 Missing ApplicationOptions attribute in user object created by New-CsHybridApplicationEndpoint cmdlet in Skype for Business Server 2015
  • Kb4078589 High memory usage on RtcHost.exe when you deploy Shared Line Appearance in Skype for Business Server 2015
  • Kb4078588 Can’t sign in Skype for Business mobile apps after applying Skype for Business Server 2015 CU6
  • Kb4078590 Calls to Mac fail when enhanced presence privacy mode is enabled in Skype for Business Server 2015
  • Kb4078592 Push Notification not working for Skype for Business for iOS in Skype for Business Server 201
  • Kb4078587 Voice settings are intermittently reset in Skype for Business on iOS and Android

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Lync 2013 / SfB 2015 Client Update – March 2018

The February update broke us through through the FIVE THOUSAND BUILD mark to hit 15.0.5007.1000, and our March update (Kb 4018290) nudges us higher to 15.0.5015.1000.

What’s Fixed

This update fixes the following issues:

  • Kb 4089881 Outlook freezes when creating a Skype meeting in Skype for Business 2015 (Lync 2013)
  • Kb 4089880 File transfer is allowed in meetings even when EnableExternalP2PFileTransfer is set to false in Skype for Business
  • Kb 4089885 Upcoming meetings keep missing from the Meetings tab in MSI-based edition of Skype for Business
  • Kb 4089883 Wrong user name in error message when a call transfer isn’t completed in Skype for Business 2015 (Lync 2013)

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Lock your SfB meeting to prevent unwanted newcomers

Hosting back-to-back meetings is at times unavoidable, and if you’re not careful you run the risk of people joining your second meeting before the first has concluded. This potentially awkward scenario arises when you’ve used the same conference ID for both, and your newcomers blissfully join not realising the virtual meeting room is already (still) in use.

If you find yourself in this situation, I have a quick fix for you: lock the door! You can do this in the virtual sense by changing the meeting so that the only person who will be automatically admitted is the organiser – yourself.

While you have the Skype meeting open, simply click the ellipsis, select “Skype Meeting Options”, then change “These people don’t have to wait in the lobby” to be “The meeting organizer” and OK. Here it is visually:


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Lync 2013 / SfB 2015 Client Update – February 2018

The January update took us to 15.0.4997.1000 and this week Kb 4011678 pushed us through the FIVE THOUSAND BUILD mark to hit 15.0.5007.1000. Phew!

What’s Fixed

This update fixes the following issues:

  • Kb 4076534 Skype for Business client crashes when working with external contacts in Outlook
  • Kb 4076533 Can’t input messages until clicking participants list after full-screen sharing in Skype for Business 2016 and Skype for Business 2015 (Lync 2013)
  • Kb 4076532 Set the default value of the EnableRestoreOAuthUsedKeyWhenUsingCachedWebTicket key to true
  • Kb 4076531 You’re prompted for Exchange credentials when you switch to internal network for Skype for Business

What’s New / Changed

Nothing documented.

Known Issues

Nothing documented.

Continue reading ‘Lync 2013 / SfB 2015 Client Update – February 2018’ »

SfB user can’t add Delegates or Team Call members

In the process of deploying an SfB installation or maybe in the early days of go-live it’s not uncommon for users to report a problem where they’re unable to add people to their Delegates or Team-Call Group list. It’s less common to see this in established installations, but there are genuine reasons why this might happen.

When this problem occurs you’ll typically be able to see the user when you search, but the OK button won’t light up:


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Upgrading to AudioCodes IPP Manager Express 7.4

AudioCodes has refreshed IP Phone Manager Express with the 7.4 release, aligning it more – at least visually – with the current SBC look and feel.

Under the hood it’s had a significant revamp: out with SQL Express, in with mySQL.

It’s presumably due to the significance of the revamp that if you try to upgrade an existing deployment to 7.4, you’ll be told “the computer says no”:


Continue reading ‘Upgrading to AudioCodes IPP Manager Express 7.4’ »

Microsoft updates WAC/OOS pre-req’s

Getting a new Office Web Apps or Office Online Server to report “Healthy” is no mean feat, and you’ll find no shortage of blog posts with advice in that direction.


Hence it was with great interest that I noticed Microsoft has recently updated the pre-req’s. (OK, it was either back in May or only last month, it’s hard to tell).

Two things jumped out at me:

  • NET-WCF-HTTP-Activation45 & several others have been added to the server pre-req’s. The former has been in the unofficial extras list for a while now, but the others are all new:

Server 2012 R2:

Add-WindowsFeature Web-Server,Web-Mgmt-Tools,Web-Mgmt-Console,Web-WebServer,Web-Common-Http,Web-Default-Doc,Web-Static-Content,Web-Performance,Web-Stat-Compression,Web-Dyn-Compression,Web-Security,Web-Filtering,Web-Windows-Auth,Web-App-Dev,Web-Net-Ext45,Web-Asp-Net45,Web-ISAPI-Ext,Web-ISAPI-Filter,Web-Includes,InkandHandwritingServices,NET-Framework-Features,NET-Framework-Core,NET-HTTP-Activation,NET-Non-HTTP-Activ,NET-WCF-HTTP-Activation45,Windows-Identity-Foundation,Server-Media-Foundation

Server 2016:

Add-WindowsFeature Web-Server,Web-Mgmt-Tools,Web-Mgmt-Console,Web-WebServer,Web-Common-Http,Web-Default-Doc,Web-Static-Content,Web-Performance,Web-Stat-Compression,Web-Dyn-Compression,Web-Security,Web-Filtering,Web-Windows-Auth,Web-App-Dev,Web-Net-Ext45,Web-Asp-Net45,Web-ISAPI-Ext,Web-ISAPI-Filter,Web-Includes,NET-Framework-Features,NET-Framework-45-Features,NET-Framework-Core,NET-Framework-45-Core,NET-HTTP-Activation,NET-Non-HTTP-Activ,NET-WCF-HTTP-Activation45,Windows-Identity-Foundation,Server-Media-Foundation
  • A new component is required:

Microsoft.IdentityModel.Extention.dll – https://go.microsoft.com/fwlink/p/?LinkId=620072

Still reporting Unhealthy?

Wictor Wilén seems to have the definitive post on getting your WAC/OOS server healthy, but if you still draw a blank my only suggestion is to try adding the x64 and x86 versions of the VC_Redist 2013 and then “Restart-Service WACSM”.

Best of luck with it! Oh, and make sure W3SVC is running!


– G.

WAC/OOS error: Could not read settings

I was struggling with an Office Online Server recently that didn’t want to talk to me. I was able to create the OfficeWebAppsFarm OK, but then couldn’t query it (as I wanted to check its health):


PS C:\> Get-OfficeWebAppsFarm
Get-OfficeWebAppsFarm : Could not read settings from WEBAPPS. The destination is unreachable.

The fix was a simple one: the WWW service was stopped. As soon as I restarted it, I was able to execute the ‘get-farm’ commandlet OK.

PS C:\> get-service W3SVC
Status   Name               DisplayName
------   ----               -----------
Stopped  3SVC               World Wide Web Publishing Service
PS C:\> start-service W3SVC


– G.

LS Audio/Video Authentication service could not be started

I returned from holidays recently to find my Skype for Business client reporting the familiar “Limited External Calling” error.

A quick RDP to my Lab’s Edge server revealed stopped services and this error in the Event Log:


Event Properties - Event 19005, LS Audio/Video Authentication Server
LS Audio/Video Authentication service could not be started.
Exception: System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Rtc.Collaboration, Version=, Culture= neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

Filtering the Event Log by this error I saw it pops up from time to time in brief spurts, then vanishes as quickly as it arrived. The date-stamp of its first recent occurrence looked interesting – that turned out to be the date I applied CU6 to the server. I’m guessing I was distracted or maybe rebooted it “into service” (ha!) and moved on to something else without checking it properly.

The fix was to run bootstrapper and it came good straight away.

PS C:\Program Files\Skype for Business Server 2015\Deployment> .\Bootstrapper.exe
PS C:\Program Files\Skype for Business Server 2015\Deployment> Start-CsWindowsService


– G.