Beware: The Updates for Dot Net that can blow our Lync or Skype Deployment: Block DOTNET (.net) 4.6.1

Good day, Happy Friday to all. I wanted to put out two warnings about updates that may cause significant problems to Skype For Business Server.

At the time of this writing 5/20/2016, there may be a problem with DOT NET 4.6.1 updates. repairing will require removal of 4.6.1 and blocking the update from being applied.

I wanted to add this document from Microsoft, which underscores the Issue- MS on Lync Exchange Compatibility

DOT Net 4.6.1 Is something you want to Block. This Link is KB 3133990. It explains that you want to ad a key called WU to the registry location HKEY_LOCAL_MACHINE\Software\Microsoft\NET Framework Setup\NDP\. then add BlockNetFramework461. Its value will be 1.

TO Recap: First Step

1. Navigate to HKEY_LOCAL_MACHINE\Software\Microsoft\NET Framework Setup\NDP

2. Ad a new Key called WU

3. Ad a new DWORD called NDPBlockNetFramework461

4. Set the Value of NDPBlockNetFramework461 to 1

Then stop all lync/sfb services


Second Step

Remove the following KBS from the programs and features, on each of the Lync servers:






Reboot when Prompted. On each of the Lync Servers, run the following command at about the same time on all servers.


Reinstall any .Net 4.5.2 updates with Windows Update.  Do not select anything that has 4.6.1 in the title if they are in the list.

Reboot when prompted

Apply any .Net 4.5.2 Security Updates with Windows Update.  These might have been done in the previous step, but we want to make sure.

Reboot if needed.


I hope this helps somebody in need.



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