Hyper-V virtual machines cannot be connected to sometimes when TCP connections reconnect in Windows

Applies to: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 EssentialsWindows Server 2012 R2 Foundation More

This article describes an issue when TCP connections reconnect in Windows Server 2012 R2 or Windows Server 2008 R2 Service Pack 1 (SP1). A hotfix is available to resolve this issue. The hotfix has a prerequisite.


This issue occurs when a node of a failover cluster is removed from active cluster membership. Additionally, the following events are logged in the System log together with corresponding time stamps:Note The Computer, Date, and Cluster node values vary, depending on the environment.


To resolve this issue, install the update rollup 2975719, or install the hotfix that is described in the "Hotfix information" section.

Update information

For more information, click the following article number to view the article in the Microsoft Knowledge Base:
2975719 August 2014 update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, go to the following Microsoft website: Note The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


To apply this update, you must have update 2919355 installed in Windows 8.1 or Windows Server 2012 R2. Or, you must have Service Pack 1 installed in Windows 7 or Windows Server 2008 R2.

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

This issue occurs when a TCP connection breaks and then reconnects. A TCP acknowledgement is not received in the node-to-node communication on a Windows Server 2012 R2 failover cluster, and the node that does not receive the TCP acknowledgement is removed from the active failover cluster membership. Error 5023 is logged in the cluster.log file of the node that is removed from the active failover cluster membership. For example, the following error 5023 is logged in the cluster.log file on the FC-NODE2 node that corresponds to the previous System log:
00000b7c.00001254::Date-Time WARN [PULLER FC-NODE2] ReadObject failed with GracefulClose(1226)' because of 'channel to remote endpoint fe80::####:####:####:####%##:~49256~ is closed'.
00000b7c.00000fa8::Date-Time ERR [CORE] mscs::NodeObject::OnMessageReceived: (5023)' because of 'Can't remove sent messages from an empty sent messages queue.'
00000b7c.00000fa8::Date-Time ERR [NODE] Node 8: Error processing message from n1, starting Regroup.

fe80::####:####:####:####%## represents the hexadecimal number that represents an IPv6 address.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates