Windows 10 Pro, RDP Server, "An internal error has occurred"

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 :)

https://social.technet.microsoft.com/Forums/en-US/e1d60cc0-0096-4859-a0e7-eb7f11905737/remote-desktop-v10-error-0x4-from-mac?forum=winRDc

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

Alternatively, you can update the same from Command Prompt as Administrator by running the following.

REG ADD "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server" /v MaxOutstandingConnections /t REG_DWORD /d 65536

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.