With some web browsers, you might encounter the error ERR_SPDY_PROTOCOL_ERROR when accessing a Windows 10 Horizon Agent Direct-Connection Plug-In (formerly View Agent Direct-Connection Plug-In) or Windows 2016 Horizon Agent Direct-Connection Plug-In desktop. You can prevent this error by deactivating the HTTP/2 protocol on the desktop.


  1. Start the Windows Registry Editor.
  2. Navigate to the registry key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters.
  3. Add 2 new REG_DWORD values, EnableHttp2Tls and EnableHttp2Cleartext, to this registry key.
  4. Set both values to 0.
  5. Reboot the desktop.