How to Fix Windows Server Update Remote Desktop Gateway KB5040437 KB5040430

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  • After the July security update of Windows Server, many machines are having issues connecting on Remote Desktop Gateway.

  • The issue affects the security updates KB5040437 and KB5040430 and others (full list below).

  • This issue affects Windows servers that are configured to use the legacy RPC over HTTP protocol in the Remote Desktop Gateway software.

  • Microsoft has released a warning about this issue (in the known issues section)..

  • There are a couple of workarounds provided, which are covered below.

Impacted Devices

  • Windows Server 2022 (Update KB5040437)
  • Windows Server 2019 (Update KB5040430)
  • Windows Server 2016 (Update KB5040434)
  • Windows Server 2012 R2 (Update KB5040456
  • Windows Server 2012 (Update KB5040485)



How to Fix this issue

Important: Before trying this, create a backup of your registry first.

  • Option 1:

Disallow connections over pipe, and port \pipe\RpcProxy\3388 through the Remote Desktop Gateway software. This is a setting you will have to enable in your firewall. Because different firewall programs have different steps you may need to use the documentation for your connection and firewall software.

  • Option 2:

Edit the registry of client devices (create a backup first), by removing a key related to RDGClientTransport

  1. Open the Start Menu
  2. Search and Open Registry Editor
  3. Click Yes/Allow if prompted
  4. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\RDGClientTransport
  5. Find the key "DWORD" and set the "Value Data" to "0x0"
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