Finding information on this is difficult, I’ve built up this table after trawling through patch notes.
This section was last updated 22nd of October 2019
A German version for Skype 2015 is over on MSxFaq’s blog here
Note that the major versions of .Net (ie, 3.x and 4.x) both run side by side on a server
| .Net Version | Minimum Lync 2013 CU | Minimum Skype4B 2015 CU | Minimum Skype4B 2019 CU | Note | More Info |
|---|---|---|---|---|---|
| Security Update for .NET Framework (3156757) aka May 2017 .Net update (Affects All Versions) | Known Issues | Known Issues | Known Issues | Known Issues | Patch introduces an issue with some clients connecting and web conferencing due to changes in encryption handling. Info and workaround here |
| .Net 3.5 | Any | Any | Any | Required | Required for installation. Lives alongside 4.X |
| .Net 3.5.1 | Any | Any | Any | You may need to repair the .Net 4.x install if you install .Net 3.51 after 4.x | Example issue: https://greiginsydney.com/no-connectivity-with-the-lync-web-app/ |
| .Net 4.0 | Out Of Support | Out Of Support | Out Of Support | .Net 4.0 No longer in support | More Info: https://devblogs.microsoft.com/dotnet/support-ending-for-the-net-framework-4-4-5-and-4-5-1/ |
| .Net 4.4 | Out Of Support | Out Of Support | Out Of Support | .Net 4.4 No longer in support | More Info: https://devblogs.microsoft.com/dotnet/support-ending-for-the-net-framework-4-4-5-and-4-5-1/ |
| .Net 4.5 | Out Of Support | Out Of Support | Out Of Support | .Net 4.5 No longer in support | More Info: https://devblogs.microsoft.com/dotnet/support-ending-for-the-net-framework-4-4-5-and-4-5-1/ |
| .Net 4.5.2 | RTM | RTM | Not Supported | Skype4B 2013 CU6 and up require at least this version. Also required for Seafutil/OOS/OWAS | Recommended for new 2013 builds Download here (why are you building a 2013 server?) |
| .Net 4.6.0 | RTM | CU 5 – May 2017 | Not Supported | Has security vulnerabilities update to 4.6.2 | 2015: Conflicting info on this one, best idea is to update to CU5 and .net 4.7.2 |
| .Net 4.6.1 | Not Supported | Not Supported | Not Supported | Not Supported on anything! Upgrade to 4.6.2 if possible Otherwise downgrade to 4.6.0 | Warning: https://tomtalks.blog/2016/02/dont-install-net-framework-4-6-1-and-skype-for-business-server-2015-lync-server-2013-exchange-server/ Block install: https://support.microsoft.com/en-us/help/3133990/how-to-temporarily-block-the-installation-of-the-net-framework-4-6-1 Removal: http://www.expta.com/2016/02/how-to-uninstall-net-framework-461.html |
| .Net 4.6.2 | CU 4 HF1 – Feb 2017 | CU 4 HF1 – Feb 2017 | Not Supported | Last supported .Net for Lync 2013 | 2019: Installer fails https://github.com/MicrosoftDocs/OfficeDocs-SkypeForBusiness/issues/2644 |
| .Net 4.7.0 | Not Supported | CU 5 – May 2017 | RTM | 2015 Ref: https://docs.microsoft.com/en-us/skypeforbusiness/plan-your-deployment/requirements-for-your-environment/server-requirements%C2%A0 | |
| .Net 4.7.1 | Not Supported | CU 5 – May 2017 | RTM | ||
| .Net 4.7.2 | Not Supported | CU 5 – May 2017 | RTM | Download here: https://download.microsoft.com/download/6/E/4/6E48E8AB-DC00-419E-9704-06DD46E5F81D/NDP472-KB4054530-x86-x64-AllOS-ENU.exe | |
| .Net 4.8 | Not Supported | CU 9 – June 2021 | RTM | Current recommended .Net for Skype4B 2015 and 2019 | Download here: https://support.microsoft.com/en-au/help/4503548/microsoft-net-framework-4-8-offline-installer-for-windows 2015 Ref: https://docs.microsoft.com/en-us/skypeforbusiness/plan-your-deployment/requirements-for-your-environment/server-requirements |
Server Updates
Updates for Skype for Business Server 2015 – Always points to the latest update.
Luca Vitali maintains a cache of older updates on his website. Skype4b 2015 and Lync 2013
A list of versions and their build numbers is over on Andrew Morpeth’s blog https://ucgeek.co/lync-updates/
Article Change Log
05/07/2021 – Added .Net 4.8 as supported for Skype4B 2015 CU 9 – Thanks Tobie