September 2026 Windows Updates Impacting Citrix VDAs
Overview
Citrix has reported multiple issues affecting Virtual Delivery Agents (VDAs) after installation of Microsoft’s September 2026 Windows updates. Affected platforms include Windows Server 2016, 2019, 2022, 2025, and Windows 11.
Issues
1. New connections start hanging a few hours after reboot with “Connecting…” and existing users are unable to log off.
The following signatures are indicative of this particular issue:
- TerminalServices-RemoteConnectionManager Event 20498: “Remote Desktop Services has taken too long to complete the client connection”
- Winlogon Event 6005: “The winlogon notification subscriber SessionEnv is taking long time to handle the notification event (Disconnect)”
- TermService status:
StopPendingrather thanRunning
2. Black Screens on Login after installing KB5124008 / KB5120998 on Desktop OS VDAs
Resolution
Microsoft has released out-of-band (OOB) patches to remediate the Remote Desktop Services (RDS) issue. The relevant patches are listed below.
- Windows 11, version 26H1: KB5129194
- Windows 11, versions 25H2 and 24H2: KB5129195
- Windows 11, versions 25H2 and 24H2 (hotpatch): KB5129241
- Windows 11, version 23H2: KB5129242
- Windows Server 2025: KB5129235
- Windows Server 2022: KB5129237
- Windows 10, version 22H2 and Windows 10 Enterprise LTSC 2021: KB5129236
- Windows 10 Enterprise LTSC 2019 and Windows Server 2019: KB5129238
- Windows 10 Enterprise LTSB 2016 and Windows Server 2016: KB5129239
- Windows Server 2012 R2: KB5129243
- Windows Server 2012: KB5129244
*Customers on older platforms will be supported as per their extended support considerations.
To download the required patches, sign in to the Microsoft catalog update page, search for the relevant KB number, download the patch, install and reboot the machine.
More Information
https://support.citrix.com/external/article/CTX697101/issues-with-microsoft-windows-september.html