I have a Windows 10 Pro machine that is functioning as a RDP terminal for a single user.

This machine was configured more than 2 years ago and has had no major changes made to its configuration, except of course for the obligatory Windows 10 automatic updates.

Everything has been working fine until a few months ago, when the user started getting this error when window attempting to connect via RDC:

Remote Desktop Connection
An internal error has occurred.

I tried logging in via RDC via my Admin credentials, and I get the same error. The error appears immediately after clicking connect. There is no processing time and the connection attempt seem to be immediately rejected by the server.

I can't trace the problem down to any specific time, or event. It occurs seemingly at random. Sometimes after a few days, sometimes twice in one day.

Restarting the Windows 10 Pro machine always seems to fix the problem.

Strangely, accessing the Event Viewer on the Windows 10 Pro machine also seemed to fix the problem, but it almost always returns much more quickly if I use this "fix".

Speaking of the Event Viewer, these are relevant errors I found in the log related to RDC at the time that my login was rejected:

Error Event 227 RemoteDesktopServices-RdpCoreTS
    General: 'Failed OnConnected to Listener callback' in CUMRDPConnection::InitializeInstance at 606 err=[0x8007050c]
    Log Name: Microsoft-Windows-RemoteDesktopServices-RdpCoreTS/Operational
    Source: RemoteDesktopServices-RdpCoreTS
    EventID: 227
    Task Category: RemoteFX module
    Level: Error
    OpCode: Runtime

Error Event 227 RemoteDesktopServices-RdpCoreTS
    General: spCoreConnection is NULL!' in CUMRDPConnection::TerminalInstance at 741 err=[0x8007139f]
    Log Name: Microsoft-Windows-RemoteDesktopServices-RdpCoreTS/Operational
    Source: RemoteDesktopServices-RdpCoreTS
    EventID: 227
    Task Category: RemoteFX module
    Level: Error
    OpCode: Runtime

These are some other errors I noticed in the log, but don't correspond to the moment I try to connect:

Warning Event 226, RemoteDesktopServices-RdpCoreTS
    General: RDP_TCP: An error was encountered when transitioning from StateUnknown in response to Event_Disconnect (error code 0x80070040)

Warning Event 142, RemoteDesktopServices-RdpCoreT
    General: TCP socket READ operation failed, error 64

Note that the client machines are also running Windows 10 Pro.

  • 2
    RemoteFX is know for trouble, try to disable it to make a test; HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client] "EnableAdvancedRemoteFXRemoteAppSupport"=dword:00000000 – yagmoth555 - GoFundMe Monica Oct 4 '18 at 18:20
  • What is RemoteFX? – Daniel Oct 6 '18 at 1:19
  • 3
    It's known for trouble. – womble Oct 17 '18 at 4:25
  • I'd like to know what I'm disabling and why before I disable it. – Daniel Nov 9 '18 at 20:22

11 Answers 11


May be a bit late but this worked for me, credit to Elton Saul. Create the DWORD below and set to 10000 My next task is to find out why it has outstanding connections :)


A temporary workaround for this issue is to increase the maximum outstanding connections limit. On client SKUs it is 100 by default, while on server SKUs it is 3000. The following DWORD registry key controls this value:

Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\
DWORD: MaxOutstandingConnections
VALUE: 10000

I've expirenced this issues several times lately, and one workaround is to connect to the machine locally if possible (or via a VmWare console).

Otherwise you can restart the Remote Desktop Services in services.msc (and say yes to also restart the dependant service).

But a permanent solution would be preferable.

  • I'm now experiencing this on another unrelated computer. Still Windows 10 Professional, but completely different hardware and configuration. But the exact same "Internal Error" problem with connecting via Remote Desktop, which presents intermittently. I never had any problems with Windows 10 and Remote Desktop until about a year ago, so I'm assuming one of the newer revisions of Windows 10 introduced this problem. :( – Daniel Nov 9 '18 at 20:25
  • Yeah, I've never seen it either, but have begun seeing it on some of my colleagues computers a couple of months ago. Restarting the Remote Desktop Service seems to help, but it can happen again later. – Holger Nov 15 '18 at 9:40

Deleting saved credentials in the client.rdp session and re-entering solved the problem for me. Edit Delete


The same error occurs with Windows Server 2019.

In addition to the Eventlog entries above I see Error Event 1006 Microsoft-Windows-TerminalServices-RemoteConnectionManager/Admin The RD Session Host server received large number of incomplete connections. The system may be under attack.

Using Wireshark I only see one connection attempt. The Server sends TCP RST what obviously causes the eventlog entries we see. Maybe the defaults from older versions of Windows got discarded. I have set MaxOutstandingConnections to 3000 as @Dexmox reposted here and can confirm it works on both Server and Client Versions of Windows.

$registryPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Terminal Server"
$Name = "MaxOutstandingConnections"
$value = 3000

IF(!(Test-Path $registryPath))
    New-Item -Path $registryPath -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name $name -Value $value -PropertyType DWORD -Force | Out-Null}
    New-ItemProperty -Path $registryPath -Name $name -Value $value -PropertyType DWORD -Force | Out-Null}

Any Windows 10 update can break anything in the system, including making it unbootable.

You will have to know when the RDP stopped working, check what update applied at that point and remove that update. TCP 64 error was found to appear after updates in several cases. So make sure you find the update that did it and also try to install update KB3200970 if you don't have it already.


I have encountered similar errors with RDP and found that disabling local resource sharing resolved the issues for me.


Under advanced tab of the RDP connection find "if server authentication fails". The default is set to Warn me. Change it to "connect and don't warn me". This just worked for me on multiple machines.


Try deleting saved credentials from RDP session. Then re-enter and save. Use RDP template below. This worked for me on three machines where I kept getting the "internal fault" error while connecting.

update try this example. Change full address X.X.X.X and USERNAME then save as


screen mode id:i:2
use multimon:i:0
session bpp:i:24
connection type:i:7
disable wallpaper:i:0
allow font smoothing:i:0
allow desktop composition:i:0
disable full window drag:i:1
disable menu anims:i:1
disable themes:i:0
disable cursor setting:i:0
full address:s:X.X.X.X
autoreconnection enabled:i:1
authentication level:i:2
prompt for credentials:i:0
negotiate security layer:i:1
alternate shell:s:
shell working directory:s:
use redirection server name:i:0

As of some Windows update within the past 9 months, this problem no longer occurs. So I assume that Microsoft finally got it sorted out.


Restarting the Remote Desktop Service worked for me. You don't have to conect locally to do that. In your local computer run services.msc then go to Action, connect to another computer, and choose the remote computer. Once connected find the service and restart it.


I seem to have encountered the same issue. For me none of the above answers solved it, but I was able to connect again after I restarted the Remote Desktop Licensing service.

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