Skype for Business Blog articles

Announcing “Period 2” for Skype for Business Server 2015/2019 Extended Security Update (ESU) Program

Paulkwo — Wed, 15 Apr 2026 14:39:10 GMT

While both Skype for Business (SfB) Server 2015 and 2019 have been out of Support since October 2025, some of our customers who needed more time to finalize migrations to SfB Server Subscription Edition (SE) or to Teams opted to enroll into the Extended Security Update program. That ESU program started in October 2025, and is concluding at the end of April 2026.

As the end of ESU draws near, some of our customers told us that they will need additional time to finalize their SfB Server 2015/2019 migrations.

Today, we are announcing that we have created a “Period 2” for the SfB Server ESU program. This period will be another 6 months, lasting from the start of May 2026, through the end of October 2026. There will be no further extensions of this program after that.

Conditions of the “Period 2” ESU program

Customers who wish to enroll in the Period 2 program will have to re-purchase the ESU for the SfB servers they need to cover during Period 2. Period 2 is not an “extension” of the current (i.e. Period 1) SfB ESU program and your organization does not automatically enroll into Period 2, either. You will have to proactively purchase ESU specifically for this new time period from May 2026-October 2026 (in the same way that you purchased the original ESU).

It is not necessary to have purchased Period 1 ESU to participate in Period 2.

After a purchase is completed, the participating organization will receive information on how to download the updates released under the Period 2 ESU. The Period 1 ESU program instructions will not work for ESU updates released after April 2026.

Starting today, customers can contact their Microsoft account team to get pricing information and purchase Period 2 ESU for their SfB 2015 and SfB 2019 servers.

What does this mean?

This Period 2 ESU is not an “extension of the support lifecycle” (Microsoft Lifecycle Policy | Microsoft Learn) for Skype for Business Server 2015 and 2019. Those servers are still out-of-support as of October 14, 2025, and you will not be able to open support cases for them (unless directly related to an issue with a SU released to ESU customers during the ESU period).
This Period 2 ESU is a way for customers who are unable to finalize their migrations to SfB Server SE or Teams before the end of April 2026, to receive Critical and Important Security Updates (as currently defined by Microsoft Security Response Center (MSRC) scoring) during Period 2. If there are SUs that we need to release, we will privately provide such SUs to ESU customers only. SfB Server 2015 and 2019 SUs will not be released on public Download Center.
SUs are released only if Critical or Important security issues are discovered in the product. We will confirm with ESU participants each Patch Tuesday whether an SU was provided or not.
This Period 2 ESU will be valid for 6 months only (from May through October, 2026).

FAQs

Why does Microsoft require an additional purchase for Period 2 of this ESU if our organization already has the original SfB Server ESU?
The first period was priced appropriately for a 6-month program, so a second 6-month period must be purchased separately.

How are SfB Server ESU updates distributed?
Updates released under Period 2 SfB ESU will follow the same process as updates released under the original ESU program: Once enrolled, your organization will be provided information on how to access any ESU updates released during Period 2.

Our organization has Microsoft Volume Licensing. Do we get the SfB ESU automatically?
No. The SfB ESU program is a separate contract that each organization must explicitly purchase via their Microsoft account team.

Help! We purchased the ESU (original or Period 2) – but we do not know how to access the updates!
If you have already purchased the ESU and need information on accessing the latest Security Updates, please contact us by sending an email to ExchangeandSfBServerESUInquiry@service.microsoft.com.

A similar program is available for our Exchange Server customers. Please read more here: Announcing Period 2 Exchange 2016/2019 Extended Security Update (ESU) program

The Skype for Business Server Team

No Skype for Business Server Security Updates for April 2026

Paulkwo — Tue, 14 Apr 2026 16:55:29 GMT

Although Skype for Business 2015 and 2019 are now out of support, some customers have purchased the Skype for Business 2015 and 2019 Extended Security Update (ESU). We have therefore decided that until the end of this Skype for Business 2015 and 2019 ESU period (April 2026) we will make an explicit update related announcement even if we DO NOT release anything for that particular month. 

There are no security releases for any version of Skype for Business Server in April 2026, for customers with SfB 2015/SfB 2019 ESU, or SfB SE.

Please keep upgrading your organizations to Skype for Business SE.

The Skype for Business Team

Skype for Business Basic Client Update – New Version Released

Paulkwo — Wed, 18 Mar 2026 16:46:35 GMT

We’re pleased to announce the availability of a new Skype for Business Basic Client.

The following notes are also presented in KB Article: KB5070432

Summary

Skype for Business Basic client is a feature reduced version of the Skype for Business client that is intended for users who do not have a license for the full Skype for Business client. For more information on the differences between the Basic client and the Full client, please see Desktop client feature comparison for Skype for Business Server 2019

Microsoft 365 Apps for Windows

This is the latest version of the Skype for Business Basic client that can be installed by users who have no version of Office installed, or by users which have Microsoft 365 Apps for Windows installed, but do not have a Skype for Business license.

Microsoft 365 Apps for Windows installer:  Download the Skype for Business Basic client

Important! This installer is not compatible with Office LTSC installations. We are currently evaluating options to enable installation of Skype for Business Basic client along-side these versions.

Office 2016 MSI

The Skype for Business 2016 Basic client is a legacy version which is no longer supported. We continue to provide access to this version for backwards compatibility; however, it will be removed at a later date.

Office 2016 MSI installer:  Download the Microsoft Skype for Business 2016 Basic client

Thank you for your continued use of Skype for Business and for your ongoing feedback, which helps guide our servicing efforts.

The Skype for Business Team

No Skype for Business Server Security Updates for March 2026

Paulkwo — Tue, 10 Mar 2026 16:59:11 GMT

There are no security releases for any version of Skype for Business Server in March 2026, for customers with SfB 2015/SfB 2019 ESU, or SfB SE.

Please keep upgrading your organizations to Skype for Business SE.

The Skype for Business Team

Skype for Business for Mac Client Update – Version 16.31.31 Released

Paulkwo — Fri, 20 Feb 2026 18:48:48 GMT

We’re pleased to announce the availability of Skype for Business for Mac client version 16.31.31, the latest update for customers who continue to rely on Skype for Business in their daily communications.

This release focuses on maintaining compatibility, reliability, and overall client quality on macOS. As Apple continues to evolve the platform, staying current with supported frameworks and tooling is essential to ensuring a stable and secure experience for our customers. Version 16.31.31 reflects our ongoing commitment to keeping the Skype for Business Mac client aligned with modern macOS requirements.

Customers using Skype for Business on Mac are encouraged to move to this latest version to benefit from the most up‑to‑date client build and to ensure continued supportability. As always, we recommend keeping clients current to minimize issues and take advantage of ongoing servicing improvements.

You can download the latest Skype for Business for Mac client from the Microsoft Download Center (Download Skype for Business on Mac from Official Microsoft Download Center), and review update information on the What’s New in Skype for Business page for the latest update information.

Note that for the time being, we have left the previous Skype for Business on Mac download (Version 16.31.11) as an available download in case you still need it during your upgrade process. But, it is no longer the supported client and at some to-be-determined time in the future, this old version will be removed from the download page.

Thank you for your continued use of Skype for Business and for your ongoing feedback, which helps guide our servicing efforts.

The Skype for Business Team

No Skype for Business Server Security Updates for February 2026

Paulkwo — Tue, 10 Feb 2026 18:00:11 GMT

There are no security releases for any version of Skype for Business Server in February 2026, for customers with SfB 2015/SfB 2019 ESU, or SfB SE.

Please keep upgrading your organizations to Skype for Business SE.

The Skype for Business Team

No Skype for Business Server Security Updates for January 2026

Paulkwo — Tue, 13 Jan 2026 17:55:20 GMT

There are no security releases for any version of Skype for Business Server in January 2026, for customers with SfB 2015/SfB 2019 ESU, or SfB SE.

Please keep upgrading your organizations to Skype for Business SE.

The Skype for Business Team

No Skype for Business Server Security Updates for December 2025

Paulkwo — Tue, 09 Dec 2025 18:00:07 GMT

There are no security releases for any version of Skype for Business Server in December 2025, for customers with SfB SE, or SfB 2015 or 2019 ESU.

Please keep upgrading your organizations to Skype for Business SE.

The Skype for Business Team

No Skype for Business Server Security Updates for November 2025

Paulkwo — Sun, 07 Dec 2025 18:26:40 GMT

There are no security releases for any version of Skype for Business Server in November 2025, for customers with SfB SE, or SfB 2015 or 2019 ESU.

Please keep upgrading your organizations to Skype for Business SE.

The Skype for Business Team

Retirement Date for Office Online Server (OOS) has been Announced

Paulkwo — Tue, 21 Oct 2025 18:58:22 GMT

We want to let our Skype for Business Server customers know that the Office Online Server (OOS) team has announced product retirement on December 31, 2026: Announcing the retirement for Office Online Server.

Office Online Server (formerly known as Office Web Apps Server) is an optional component that can be integrated with Skype for Business Server on-premises and it provides the ability to work with supported types of file attachments in various scenarios without having to download them, first.

What Skype for Business Customers Lose When Office Online Server Retires

Microsoft Office Online Server (OOS) has provided enhanced PowerPoint experiences in Skype for Business meetings. With its upcoming retirement, organizations relying on Skype for Business should understand what functionality will disappear, and why it matters.

Key Features Going Away

When OOS is removed from your environment, these capabilities will no longer be available:

High-Fidelity PowerPoint Rendering
OOS processes PowerPoint files on dedicated servers, delivering animations, transitions, and embedded media with near-native quality. Without it, PowerPoint presentations may only be shared via screen sharing.

Presenter Notes
Presenters currently have private access to notes during meetings, which will go away without OOS. Alternatives are separate devices or printed notes. If using screen sharing, notes would still be available for the presenter on a secondary screen.

In-Meeting Annotations
Today, participants can highlight, draw, and stamp directly on slides without altering the original file. After OOS retirement, this interactive collaboration is no longer available.

Embedded Video Playback
Videos embedded in PowerPoint slides play via OOS. Post-retirement, these videos will play back with lower fidelity in Skype for Business meetings when screen sharing.

Why This Matters

If your organization relies on presentations using the OOS-enabled features called out, above, the loss of OOS will impact meeting quality. Plan ahead by migrating to Microsoft Teams or adjusting workflows.

What Remains

Basic screen sharing will still work. Features like whiteboards, polls, and app sharing remain unaffected.

FAQ: Office Online Server (OOS) Retirement and Impact on Skype for Business

Q1: What is happening to Office Online Server?

Office Online Server is being retired and will no longer be supported by Microsoft. This affects organizations using Skype for Business for rich PowerPoint presentations.

Q2: What functionality will we lose in Skype for Business meetings?

Without OOS, these features will no longer be available:

High-fidelity PowerPoint rendering (animations, transitions, embedded media)

Presenter notes visible only to presenters

In-meeting annotations (drawing, highlighting, stamping)

Embedded video playback within PowerPoint slides

Q3: Will basic screen sharing still work?

Yes. You can still share your screen or application window, but it lacks the advanced capabilities OOS provided.

Q4: Are other Skype for Business features affected?

No. Features like whiteboards, polls, and app sharing remain unchanged.

Q5: Will OOS stop working after the retirement date?

No. Microsoft will not actively block usage of OOS with Skype for Business Server after its retirement. However, OOS will no longer be maintained with bug fixes and features, and no further security updates will be provided.

Q6: What should we do to prepare?

Consider:

Migrating to Microsoft Teams, which offers modern meeting experiences.

Adjusting workflows for presentations (e.g., using screen share or Teams Live Events).

The Skype for Business Team

Support for Skype for Business Server 2015 and Skype for Business Server 2019 ends today

Paulkwo — Tue, 14 Oct 2025 16:01:58 GMT

Today, October 14, 2025,  Skype for Business Server 2015, Skype for Business Server 2019, Skype for Business 2016 (client), and Skype for Business 2019 (client) reach end of support. It’s therefore critical to upgrade now to remain supported and secure.

Microsoft will no longer provide technical support, meaning some problems may occur with these products. Users will no longer receive:

Bug fixes for issues that may impact the stability and usability of the server or clients.

Security fixes for vulnerabilities that may make the server or clients vulnerable to security breaches.

Customer installations of Skype for Business Server 2015 and Skype for Business Server 2019 and clients running Skype for Business 2016 and Skype for Business 2019 will continue to run after today. However, continuing to use these offerings after the end-of-support date invites potential future security risks, so we strongly recommend taking immediate action.

Our recommendation is to migrate to Microsoft Teams or upgrade your organization to Skype for Business Server Subscription Edition (SE).

Migrate to Microsoft Teams

Customers get the best value and user experience by migrating from Skype for Business Server to Microsoft Teams. Migrating to Microsoft Teams is the best and simplest option to help you retire your Skype for Business Server deployment.

When you migrate to Microsoft Teams, you make a straightforward hop away from an on-premises deployment and benefit from new features and technologies, including advanced generative AI technologies that provide meeting summaries, that are available in the cloud but not on-premises.

If you're migrating to Microsoft 365, you might be eligible to use our Microsoft FastTrack service. FastTrack shares best practices and provides tools and resources to make your migration to Microsoft 365 as seamless as possible. Best of all, you’ll have a support engineer helping you, from planning and designing to migrating your last mailbox. For more information about FastTrack, see Microsoft FastTrack.

Prepare to Upgrade to Skype for Business Server SE

In July 2025, we announced the general availability of Skype for Business Server SE with details on how to upgrade if you intend to continue to run Skype for Business Server on-premises.

If you are running Skype for Business Server 2019, we recommend that you upgrade in-place to Skype for Business Server SE.
If you are running Skype for Business Server 2015, we recommend that you perform a legacy (a.k.a. side-by-side) upgrade to Skype for Business Server SE.

Skype for Business Technology Adoption Program

If your organization intends to continue running Skype for Business Server and you want to test and evaluate pre-release builds of Skype for Business Server SE, you can apply to join the Skype for Business Technology Adoption Program (TAP).

Joining the TAP has several advantages, such as the ability to provide input and feedback on future updates, develop a close relationship with the Skype for Business engineering team, receive pre-release information about Skype for Business, and more. TAP members also get support from Microsoft at no additional charge for issues related to the TAP.

All nominations are reviewed and screened prior to acceptance. No customers are allowed access to any pre-release downloads or information until all legal paperwork is properly executed. Nomination does not mean acceptance, as not all nominees will be chosen for the TAP. If you are preliminarily accepted, we will contact you to get the required paperwork started.

Related Microsoft Products Reaching End of Support on October 14, 2025

In addition to the above Skype for Business products, several other products (some of which are often used with Skype for Business) also reach end of support or retirement on October 14, 2025, including Exchange Server 2016, Exchange Server 2019, Microsoft Office 2016, Microsoft Office 2019, Outlook 2016, Outlook 2019, Windows 10, and more.

You can search product and services lifecycle information to get detailed information for your Microsoft products and services.

– Skype for Business Server Engineering Team

Hotfix Released for Skype for Business Server SE (SE RTM Hotfix 2)

Paulkwo — Tue, 30 Sep 2025 17:31:02 GMT

Microsoft has released a hotfix update for Skype for Business Server Subscription Edition (Version 7.0.2046.828) to resolve two issues impacting functionality:

MACP Icons Not Loading Offline: Icons in the MACP interface were failing to load when the server was accessed without an internet connection. (KB5067476)

Export-CsRGSConfiguration Command Failure: The Export-CsRGSConfiguration PowerShell command was not executing properly on Skype for Business SE Edition Server. (KB5067477)

This update addresses both problems and improves overall stability.

You can download this latest build here: Download Skype for Business Server Subscription Edition RTM Hotfix 2 KB5065372 from Official Microsoft Download Center

– Skype for Business Server Engineering Team

T-1 month: Skype for Business Server 2015 and Skype for Business Server 2019 End of Support

Paulkwo — Mon, 15 Sep 2025 15:48:47 GMT

September 14, 2025

On October 14, 2025, one month from now, Skype for Business Server 2015, Skype for Business Server 2019, Skype for Business 2016 (client), and Skype for Business 2019 (client) reach end of support. It’s therefore critical to upgrade now to remain supported and secure.

After October 14, 2025, Microsoft will no longer provide technical support, meaning some problems may occur with these products. Users will no longer receive:

Bug fixes for issues that may impact the stability and usability of the server or clients.

Security fixes for vulnerabilities that may make the server or clients vulnerable to security breaches.

Customer installations of Skype for Business Server 2015 and Skype for Business Server 2019 and clients running Skype for Business 2016 and Skype for Business 2019 will continue to run after October 14, 2025. However, continuing to use these offerings after the end-of-support date invites potential future security risks, so we strongly recommend taking immediate action.

Our recommendation is to migrate to Microsoft Teams or  upgrade your organization to Skype for Business Server Subscription Edition (SE).

Migrate to Microsoft Teams

Prepare to Upgrade to Skype for Business Server SE

In July 2025, we announced the general availability of Skype for Business Server SE with details on how to upgrade if you intend to continue to run Skype for Business Server on-premises.

If you are running Skype for Business Server 2019, we recommend that you upgrade in-place to Skype for Business Server SE.

If you are running Skype for Business Server 2015, we recommend that you perform a legacy (a.k.a. side-by-side) upgrade to Skype for Business Server SE.

Skype for Business Technology Adoption Program

Related Microsoft Products Reaching End of Support on October 14, 2025

You can search product and services lifecycle information to get detailed information for your Microsoft products and services.

– Skype for Business Server Engineering Team

Released: August 2025 Skype for Business Server Hotfix Updates

Paulkwo — Mon, 18 Aug 2025 17:00:06 GMT

Summary

Microsoft has released Hotfix Updates (HUs) for Skype for Business (SfB) Server that introduces support for a new security-related feature. Starting with the August 2025 Hotfix (HF), Skype for Business Server has the capability to configure a Dedicated Hybrid Application to ensure secure and reliable hybrid integration with Exchange Online.

Additionally, this release includes updates for the Skype Meetings Application. After October 15, 2025, the Skype Meetings Application may not function correctly unless this Hotfix is installed.

Note: For Skype for Business Server 2015, administrators must also run the add_sfbassets.ps1 script after installing the update to ensure continued functionality of the Skype Meetings Application. The script is available on the SfB 2015 Download Center Page.

Supported Versions

Hotfix Updates are available for the following versions:

Skype for Business Server 2015 CU13 (KB3061064)

Skype for Business Server 2019 CU8 (KB4470124)

Skype for Business Server Subscription Edition (SE) RTM (KB5065372)

What’s Changing?

Previously, Skype for Business Server utilized a Microsoft-managed Shared Service Principal for authentication and access to Exchange Online in support of hybrid features, including:

Archiving to Exchange Online

Calendar-based presence

Profile picture synchronization

With this release, organizations can (and should) configure a customer-managed Dedicated Hybrid Application within their Microsoft Entra ID tenant. Failure to implement this configuration will result in the discontinuation of hybrid features as outlined in Plan to integrate Skype for Business and Exchange.

From the following server versions onward, Skype for Business provides support for the Dedicated Hybrid Application:

Server Version	Minimum Build
Skype for Business Server 2015	6.0.9319.881
Skype for Business Server 2019	7.0.2046.553
Skype for Business Server SE	7.0.2046.820

Details regarding the prerequisites and steps required to set up the Dedicated Hybrid Application for Skype for Business are available in the Configure dedicated hybrid application in Skype for Business Server documentation.

The Skype for Business Server Team

Announcing Skype for Business 2015 / 2019 Extended Security Update program

Paulkwo — Wed, 15 Apr 2026 14:52:49 GMT

EDIT 4/15/2026: We have now announced Period 2 of this ESU program which needs to be purchased separately. If your organization requires SfB ESU between May and October 2026, you will have to re-purchase the ESU. Please see Announcing “Period 2” for Skype for Business Server 2015/2019 Extended Security Update (ESU) Program | Microsoft Community Hub for more information.

With both Skype for Business 2015 and 2019 going out of support in October 2025, we have heard from some of our customers that they have started their migrations to Skype for Business Subscription Edition (SE), but might need a few extra months of Security Update (SU) coverage for their Skype for Business 2015/2019 servers while they are finalizing their migrations.

We are announcing that we now have a solution for such customers. Starting on August 1^st, 2025, customers can contact their Microsoft account team to get information about and purchase an additional 6-month Extended Security Update (ESU) for their Skype for Business 2015/2019 servers. Your account teams will have information related to per server cost and additional details on how to purchase and receive ESUs, starting August 1^st, 2025.

What does this mean?

This ESU is not an “extension of the support lifecycle” (Microsoft Lifecycle Policy | Microsoft Learn) for Skype for Business 2015/2019. Those servers still go out-of-support on October 14, 2025, and you will not be able to open support cases for them (unless directly related to an issue with a SU released to ESU customers during the ESU period).
This ESU is a way for customers who might not be able to finalize their migrations to Skype for Business SE before October 14, 2025, to receive Critical and Important updates (as currently defined by Microsoft Security Response Center (MSRC) scoring) as SUs that we might release after October 2025. If there are SUs that we need to release, we will privately provide such SUs to ESU customers. Skype for Business 2015/2019 SUs will not be released on public Download Center or Windows Update after October 2025.
We are not committing to actually releasing any SUs during the ESU period. Skype for Business Server does not often release Security Updates on Patch Tuesday (2^nd Tuesday of the month) as SUs are released only if there are Critical or Important security product changes. Therefore, if there are no SUs that we need to release during the time of ESU, there will be no such updates provided. We will, however, confirm with ESU participants each Patch Tuesday whether an SU was provided or not.
This ESU will be valid for 6 months only (through April 14, 2026). This period will not be extended past April 2026 (you do not need to ask).

Who is Skype for Business 2015/2019 ESU for?

This program is intended only for customers who are unable to finalize their migrations to Skype for Business SE before end of support lifecycle for Skype for Business 2015/2019, and still need Critical and Important security coverage for the older servers still in operation.

We recommend that customers do not rely on this ESU, but instead upgrade their organizations to Skype for Business SE in time.
Customers using Skype for Business 2019 should in-place upgrade to Skype for Business SE quickly and switch to the Skype for Business SE modern lifecycle policy.

Please continue migrating to Skype for Business SE in time instead of taking advantage of this ESU program. But if you really must, please contact your Microsoft account team for more details starting August 1^st, 2025.

A similar program is available for our Exchange Server customers. Please read more here: Announcing Exchange 2016 / 2019 Extended Security Update program

The Skype for Business Server Team

Skype for Business Server Subscription Edition (SE) is now available

Paulkwo — Fri, 08 Aug 2025 17:17:54 GMT

We are excited to announce the general availability of Skype for Business Server Subscription Edition (SE). This release provides a sustainable model for Microsoft to continue offering an on-premises unified communications platform that integrates instant messaging, voice and video calls, online meetings, and presence information to enhance collaboration and productivity across organizations. While Microsoft Teams and Microsoft 365 will continue to offer the latest and most innovative solutions – including the integration of Microsoft 365 Copilot – Skype for Business Server SE demonstrates our commitment to ongoing support for scenarios where on-premises solutions remain critical.

To help bring Skype for Business Server into the future, the Subscription Edition introduces some changes to the way Skype for Business is serviced and licensed. Unlike previous versions of Skype for Business, the Subscription Edition is governed by the Modern Lifecycle Policy. This means that from now on, support will have no fixed end date provided customers keep their configurations up-to-date. Instead, the Skype for Business Server SE codebase will be serviced continuously as an evergreen product, with no further major, year-numbered versions.

Release Details

As we’ve shared previously, the Skype for Business Server SE Release to Manufacturing (RTM) build can be installed as a Cumulative Update (CU) to Skype for Business Server 2019 and can be joined to your Skype for Business 2015/2019 environments. For additional information on the upgrade process, please read our detailed post from April 2025.

For customers who are already using Skype for Business Server 2019 today, our recommendation is to in-place upgrade the servers to Skype for Business Server SE, which will switch them to the Skype for Business Server SE branding. Skype for Business Server SE RTM is unlike previous Skype for Business Server RTM releases, as it uses Skype for Business Server 2019 CU8HF1 (i.e. March 2025 cumulative update 7.0.2046.548 for Skype for Business Server 2019) as the codebase and contains no major changes when compared to Skype for Business Server 2019 CU8HF1. See Why “in-place upgrade” from Skype for Business Server 2019 to Subscription Edition (SE) is low risk for more information on the in-place upgrade path and why it is highly recommended.

To ease the in-place upgrade process from Skype for Business Server 2019 to Skype for Business Server SE RTM, the following is true when comparing Skype for Business Server SE RTM to Skype for Business 2019 CU8HF1:

No features were removed or added.
No installation prerequisites were changed.

The following are the differences from Skype for Business 2019 CU8HF1:

The License Agreement (an RTF file shown only in the GUI version of Setup) was updated.
The name was changed from Microsoft Skype for Business Server 2019 to Microsoft Skype for Business Server Subscription Edition.
The build number was updated.

Please see System requirements for Skype for Business Server 2019 - Skype for Business Server 2019 | Microsoft Learn for Skype for Business Server SE installation prerequisite details.

You can download the installer for SE and the installer for PChat from: Download Skype for Business Server Subscription Edition Cumulative Update KB5065372 from Official Microsoft Download Center.

Looking forward

While the RTM release of Skype for Business Server SE is currently identical to Skype for Business Server 2019 CU8HF1, this will not remain the case. After support for Skype for Business Server 2015 and 2019 ends in October 2025, Skype for Business Server SE will be the only supported on-premises version of Skype for Business Server. This will create unique opportunities to simplify, streamline, and modernize the product over the coming years. We will continue releasing Skype for Business Server SE Cumulative Updates and Hotfixes, with Security Updates being released as needed.

As end-of-support is fast approaching, please work on upgrading your organization to Skype for Business Server SE as soon as possible and decommission the older versions. Although the introduction of Skype for Business Server SE does not change allowed coexistence with Skype for Business Server 2015 and Skype for Business Server 2019, a future CU or HF will require that no Skype for Business Server 2015 or 2019 servers are installed in the organization. Future Skype for Business Server SE CUs will also modernize the installation process, add new components to the compatibility matrix, and bring new features.

For those with multiple on-premises server needs, we’re pleased to add that Exchange Server Subscription Edition is also generally available today. You can read more about that release on the Exchange blog - Exchange Server Subscription Edition (SE) is now available.

We look forward to your feedback and thank you for your continued support of Skype for Business.

The Skype for Business Server Team

Why “in-place upgrade” from Skype for Business Server 2019 to Subscription Edition (SE) is low risk

Paulkwo — Wed, 25 Jun 2025 19:41:23 GMT

We wanted to write an article related to a very frequent customer question regarding Skype for Business (Skype for Business) Server 2019 to Skype for Business Server Subscription Edition (SE) migration.

As we mentioned in Skype for Business Server Roadmap Update – there are two ways to migrate to Skype for business server SE:

Traditional (legacy) migration:

The “Add a new Skype for Business Server to your topology and move services/users to it” approach: This is mandatory if you are moving from Skype for Business Server 2015 to Skype for Business Server SE, but is only optional if you are moving from Skype for Business Server 2019 to Skype for Business Server SE.

In-place upgrade:

The “Install Skype for Business Server SE Release to Manufacturing (RTM) build on top of Skype for Business Server 2019 (i.e. simply upgrading your existing 2019 deployment to SE)” approach: This is new, and some customers feel it’s “too good to be true” or possibly risky.

Let us explain why we view this second approach as “low risk”.

How RTM of a new Skype for Business Server version used to be created

In the past, when a new version of Skype for Business Server was released, we would make significant changes to the code base. The following is a simplification, but it gives you a general idea. Usually we would:

About two years before the release of the new version, take a version of the current in-market product as “base code” of the new product
Add and remove a bunch of features
Change installation prerequisites
Set new minimum hardware requirements
Change the major and minor build number in our build system 
Close to the release date, port over all features, security and hotfix updates released for the current in-market product since the code paths diverged (because the new version shouldn’t regress in any way)
Change the product name and update the Microsoft Software Licensing Terms

Because many of those changes were significant, this essentially required customers to do the following:

Perform a legacy (side-by-side) migration

Do a significant amount of testing in their organizations to ensure that added or removed features do not interfere with their business processes or 3rd party applications

Develop training for end users (because of significant product changes)

Wait for CU1, because RTM build was seen as “high risk” as many features were added / removed (Note: Waiting was never required/recommended by Microsoft, but we know many customers would wait for at least CU1 before migrating.)

How we created Skype for Business Server Subscription Edition RTM

As opposed to the traditional process, Skype for Business Server SE RTM was created as follows:

Started with Skype for Business Server 2019 CU8 as the base code, slightly incrementing the minor build number
Added the recent CU8 Hotfix 1 update from March ‘25
Changed the product name and updated the licensing terms

Note that the first two items, above, are part of every CU process and we have updated the licensing terms in patch updates in the past, so it is in-scope as a typical kind of change.

We did not do any of the following in Skype for Business Server SE RTM, compared to Skype for Business 2019 CU8 Hotfix 1 (i.e. March 2025 cumulative update 7.0.2046.548 for Skype for Business Server 2019)

Change the major version of code

Add / remove any features

Fix any bugs that were not already fixed in the March 2025 release

Change installation prerequisites or hardware requirements

Because of all of this, installing Skype for Business Server SE RTM on your Skype for Business Server 2019 deployment is essentially installing Skype for Business Server 2019 “CU9”, with a small payload that could be considered a minor Hotfix.

Why upgrade then? What’s the point of all this?

There are several ways in which we believe this approach takes the time pressure off your organizations:

It is a simple “no significant changes since Skype for Business 2019 CU8” installation, so there is no need for extensive testing and validation.
By upgrading to this Skype for Business ~~2019 CU9~~ SE RTM build, you switch from the Fixed lifecycle policy of Skype for Business 2019 (end of support life on October 14, 2025) to the Skype for Business SE Modern lifecycle policy and your product is supported after October 14, 2025.
Even if you want to upgrade your Skype for Business 2019 hardware for Skype for Business SE, you can in-place upgrade to Skype for Business SE first on old hardware and then, once you are on the new support lifecycle path, you have the time to upgrade your server hardware.

Conclusion

We realize that with this approach to Skype for Business Server SE RTM, we are doing something different, and we probably did not articulate enough just how different it is. As far as engineering work is concerned, Skype for Business SE RTM is a re-branded “Skype for Business 2019 CU9” with no features, meaning you can upgrade directly from any Skype for Business Server 2019 update, including 2019 RTM, to Skype for Business Server SE. We have released 8 CUs for Skype for Business 2019 already and have a high degree of confidence that this can be a very low risk action for our customers.

To Recap:

The Skype for Business Server Team

T-6 months: Skype for Business Server 2015 and Skype for Business Server 2019 End of Support

amitmanchanda — Mon, 14 Apr 2025 16:00:05 GMT

On October 14, 2025, six months from now, Skype for Business Server 2015, Skype for Business Server 2019, Skype for Business 2016 (client), and Skype for Business 2019 (client) reach end of support. It’s therefore critical to plan your upgrade now to remain supported and secure.

After October 14, 2025, Microsoft will no longer provide technical support, meaning some problems may occur with these products. Users will no longer receive:

Bug fixes for issues that may impact the stability and usability of the server or clients.

Security fixes for vulnerabilities that may make the server or clients vulnerable to security breaches.

Customer installations of Skype for Business Server 2015 and Skype for Business Server 2019 and clients running Skype for Business 2016 and Skype for Business 2019 will of course continue to run after October 14, 2025. However, continuing to use these offerings after the end-of-support date invites potential future security risks, so we strongly recommend taking immediate action.

Our recommendation is to migrate to Microsoft Teams or prepare to upgrade your organization to Skype for Business Server Subscription Edition (SE) when it becomes available in July 2025.

Migrate to Microsoft Teams

You get the best value and user experience by migrating from Skype for Business Server to Microsoft Teams. Migrating to Microsoft Teams is the best and simplest option to help you retire your Skype for Business Server deployment.

When you migrate to Microsoft Teams, you make a single hop away from an on-premises deployment and benefit from new features and technologies, including advanced generative AI technologies that provide meeting summaries, that are available in the cloud but not on-premises.

Prepare to Upgrade to Skype for Business Server SE

Last year, we provided an update to the Skype for Business Server roadmap and details on how upgrade to Skype for Business Server SE if you intend to continue to run Skype for Business Server on-premises.

If you are running Skype for Business Server 2019, we recommend that you install CU8HF1 immediately and keep your servers up to date, and then you can upgrade in-place to Skype for Business Server SE when it becomes available in July 2025.

If you are running Skype for Business Server 2015, we recommend that you perform a legacy (a.k.a. side-by-side) upgrade to Skype for Business Server 2019 now and then perform an in-place upgrade to Skype for Business Server SE once it’s released. You do have the option of upgrading from Skype for Business Server 2015 to Skype for Business Server SE, skipping Skype for Business Server 2019 completely. But since there are only a few months between the release of Skype for Business Server SE and the end of support for Skype for Business Server 2015 and Skype for Business Server 2019, that might not be enough time, depending on the size of your deployment and other factors. This is why we recommend that you upgrade to Skype for Business Server 2019 now and do an in-place upgrade to Skype for Business Server SE when it is available.

Skype for Business Technology Adoption Program

If your organization intends to continue running Skype for Business Server and you want to test and evaluate pre-release builds of Skype for Business Server SE, you can apply to join the Skype for Business Technology Adoption Program (TAP).

Related Microsoft Products Reaching End of Support on October 14, 2025

In addition to the above Skype for Business products, several other products (some of which are often used with Skype for Business) also reach end of support or retirement on October 14, 2025, including Exchange Server 2016, Exchange Server 2019, Microsoft Office 2016, Microsoft Office 2019, Outlook 2016, Outlook 2019, Windows 10, and more.

You can search product and services lifecycle information to get detailed information for your Microsoft products and services.

– Skype for Business Server Engineering Team

More licensing and pricing information for Skype for Business Server SE is now available

amitmanchanda — Fri, 04 Apr 2025 06:48:43 GMT

Quick update for awareness: more details about the timing and pricing of Skype for Business Server Subscription Edition (SE) were shared on the Microsoft 365 Blog today. Read the post here:

Licensing and pricing updates for on-premises server products coming July 2025

Your Microsoft account or Sales folks will be able to provide more details.

Hotfix Released for Skype for Business Server 2019 CU8

amitmanchanda — Tue, 11 Mar 2025 11:30:12 GMT

Hotfix for Skype for Business Server (7.0.2046.548 CU8HF1) has been released to address an issue introduced by Cumulative Update 8 for Skype for Business Server 2019. This issue caused failure in joining the meeting while using Skype Meetings app (Skype for Business Web App) in some cases. This has been fixed now. This build can be downloaded from here: Download Skype for Business Server 2019 Cumulative Update KB4470124 from Official Microsoft Download Center