Skype for Business Blog articles

Reminder: Skype for Business 2015 and 2019 ESU Program Ends in October 2026

Paulkwo — Tue, 21 Jul 2026 14:24:49 GMT

Over the last several weeks we have received several questions about possible extension of the Skype for Business Server 2015/2019 ESU program past October 2026. After all, in our original Skype for Business 2015 / 2019 Extended Security Update program announcement we said that there would be no extensions, but then we ended up creating a “Period 2” Skype for Business ESU program, that is scheduled to conclude at the end of October 2026. We are just about at the mid-point of Period 2 Exchange ESU now.

There will be no further extension of Skype for Business 2015/2019 ESU program timeline. Once October 2026 ends, there will be no further updates for Skype for Business 2015/2019, even if you currently have the Period 2 ESU.

If your organization still uses Skype for Business 2015 or 2019 in production:

See Why “in-place upgrade” from Skype for Business Server 2019 to Subscription Edition (SE) is low risk | Microsoft Community Hub – which explains why in-place upgrade from Skype for Business 2019 CU8 to Skype for Business SE RTM is not a significant technological change and is low risk.
See Support for Skype for Business Server 2015 and Skype for Business Server 2019 ends today | Microsoft Community Hub – if you are still running Skype for Business 2015.

The Skype for Business Server Team

Skype for Business Server Hybrid: Prepare for EWS Retirement in Exchange Online

Paulkwo — Mon, 20 Jul 2026 18:59:49 GMT

The Exchange team recently announced a phased retirement of Exchange Web Services (EWS) in Exchange Online, with full retirement on April 1, 2027. See Exchange Online EWS, Your Time is Almost Up for the full background.

This change affects hybrid Skype for Business Server deployments, which use EWS today to communicate with Exchange Online. To help administrators prepare, we’ve published a new guide on Microsoft Learn:

Prepare for EWS retirement in Exchange Online

The guide covers what’s changing, the two deadlines that matter, and the exact PowerShell steps to keep Skype for Business Server hybrid functionality working. This post is a short summary — please read the Learn article for the full details.

Who is affected

Only hybrid Skype for Business Server deployments — Skype for Business Server on-premises with user mailboxes in Exchange Online.

Pure on-premises deployments (Skype for Business Server with Exchange Server on-premises) aren’t affected. EWS retirement applies only to Exchange Online.

What you need to do

Before end of August 2026 — Set EwsEnabled = $true at the tenant level and add the Skype for Business Server App ID and the Skype desktop client App ID to the EWS allowed App IDs list. See Prepare for EWS retirement in Exchange Online for the required App IDs and configuration steps. This keeps Skype for Business Server EWS calls working through the phased disablement and excludes your tenant from the October 1, 2026 auto-switch to EwsEnabled = $false.
Before April 1, 2027 — Install the upcoming Skype for Business Server update, which replaces EWS calls to Exchange Online with Microsoft Graph API calls. Once installed, Skype for Business Server hybrid will continue to work after EWS is permanently retired.

Detailed steps, PowerShell scripts, and verification commands are in the Learn article: Prepare for EWS retirement in Exchange Online.

Key dates

Date	Event
End of August 2026	Deadline to configure EwsEnabled = $true and add the Skype for Business Server and Skype desktop client App IDs to the EWS allowed App IDs list.
October 1, 2026	Microsoft auto-sets EwsEnabled = $null → $false for tenants that haven’t opted in.
Before April 1, 2027	Install the upcoming Skype for Business Server update (Graph API replacement for EWS).
April 1, 2027	Full and permanent EWS retirement in Exchange Online. No exceptions.

The bottom line

If you run Skype for Business Server hybrid with mailboxes in Exchange Online, start planning now. Both deadlines are firm, and there will be no extensions past April 1, 2027. Read the full guidance in Prepare for EWS retirement in Exchange Online, and watch the Microsoft 365 Message center for the Skype for Business Server update release announcement.

No Skype for Business Server Security Updates for July 2026

Paulkwo — Tue, 14 Jul 2026 17:00:17 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 2 (October 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 July 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 June 2026

Paulkwo — Tue, 09 Jun 2026 17:10:36 GMT

There are no security releases for any version of Skype for Business Server in June 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

Cumulative Update Released for Skype for Business Server SE (SE CU1)

Paulkwo — Mon, 01 Jun 2026 19:13:55 GMT

Microsoft has released a cumulative update for Skype for Business Server Subscription Edition (Build Number 7.0.2046.849), which resolves two significant issues, in addition to other meaningful payload content:

Blank screen when accessing the Skype Meetings application after installing CU8: A white screen appears when attempting to join a meeting through the web address (“Join a meeting” link). (KB5088874)
Move-CsUser fails in latest Microsoft Teams module (7.3.0): When attempting to move a user from on-premises Skype for Business to Teams Online using the command Move-CsUser -Identity ua0017@basil.vtdeploy.net -Target sipfed.online.lync.com -Credential $cred the operation fails with an error. (KB5088873)

You can download this latest build here: Download Skype for Business Server Subscription Edition RTM CU1 KB5065372 from Official Microsoft Download Center

– Skype for Business Server Engineering Team

No Skype for Business Server Security Updates for May 2026

Paulkwo — Tue, 12 May 2026 16:59:31 GMT

There are no security releases for any version of Skype for Business Server in May 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

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

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 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

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 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

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 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

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 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

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 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

Skype for Business Blog articles

Reminder: Skype for Business 2015 and 2019 ESU Program Ends in October 2026

Skype for Business Server Hybrid: Prepare for EWS Retirement in Exchange Online

Who is affected

What you need to do

Key dates

The bottom line

Related reading

No Skype for Business Server Security Updates for July 2026

No Skype for Business Server Security Updates for June 2026

Cumulative Update Released for Skype for Business Server SE (SE CU1)

No Skype for Business Server Security Updates for May 2026

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

Conditions of the “Period 2” ESU program

What does this mean?

FAQs

No Skype for Business Server Security Updates for April 2026

Skype for Business Basic Client Update – New Version Released

Summary

Microsoft 365 Apps for Windows

Office 2016 MSI

No Skype for Business Server Security Updates for March 2026

Skype for Business for Mac Client Update – Version 16.31.31 Released

No Skype for Business Server Security Updates for February 2026

No Skype for Business Server Security Updates for January 2026

No Skype for Business Server Security Updates for December 2025

No Skype for Business Server Security Updates for November 2025

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

What Skype for Business Customers Lose When Office Online Server Retires

Key Features Going Away

Why This Matters

What Remains

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

Q1: What is happening to Office Online Server?

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

Q3: Will basic screen sharing still work?

Q4: Are other Skype for Business features affected?

Q5: Will OOS stop working after the retirement date?

Q6: What should we do to prepare?

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

Migrate to Microsoft Teams

Prepare to Upgrade to Skype for Business Server SE

Skype for Business Technology Adoption Program

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

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

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

Migrate to Microsoft Teams

Prepare to Upgrade to Skype for Business Server SE

Skype for Business Technology Adoption Program

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

Released: August 2025 Skype for Business Server Hotfix Updates