Windows Server · 2025 · Release · Out-of-band update

September 22, 2025— KB5068221 (OS Build 26100.6588) Out-of-band

Windows Server 2025: Current LTSC release

Microsoft's known issues — KB5068221

  • Issue Known issue After installing the Windows update released on or after September 9, 2025, you might fail to connect to shared files and folders using the Server Message Block (SMB) v1 protocol on NetBIOS over TCP/IP ( NetBT ). This issue can occur if either the SMB client or the SMB server has the September 2025 security update installed. Note: The SMBv1 protocol is deprecated and no longer installed by default in modern versions of Windows and Windows Server. Deployments that use newer versions of the protocol, SMBv2 or SMBv3 , are not affected by this problem. Active Directory domain controllers (DC) running on Windows Server 2025 and also running the schema master Flexible Single Master Operation (FSMO Workaround: This issue is addressed in KB5066835 . This issue is addressed KB5068861 . This issue is addressed in KB5068861 .

Microsoft's release notes for KB5068221 ›

Known issues — reported on the forum

Discussed on the forum

No member thread names 26100.6588 yet.

Search the forum for 26100.6588 Ask about this build