This bug has been added to the tracker:
https://winscp.net/tracker/1572

Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
It occurs when I try move in folder structure on MFT with keyboard button up or down.
It also occurs in previous versions of WinSCP.

Depends on type of sftp:
ON SFTP from axway: https://www.axway.com occurs this error. Also error message is from this server.

On SFTP server from: https://www.syncplify.com/ works without problem.
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.11.2

Error message:
External exception EEFFACE

Stack trace:
(0000B54F) KERNELBASE.dll.RaiseException
(00062496) ntdll.dll
(0000F13E) ntdll.dll.KiUserExceptionDispatcher
(004D0DF0)
(0089D216)
(0089E560)
(008820A0)
(0075E45A)
(0075F84C)
(007725F9)
(0076DFF1)
(0076EA29)
(007A58CA)
(00670046)
(0028E96E)
(0041E4B5)
(00257C85)
(0028EC2A)
(00257DEB)
(00257C85)
(002572CC)
(0037BC78)
(000152F7) USER32.dll
(00015D35) USER32.dll
(00015DE3) USER32.dll
(00015E41) USER32.dll
(0000F117) ntdll.dll.KiUserCallbackDispatcher
(000186C0) USER32.dll.SendMessageW
(0002B06D) COMCTL32.DLL
(000A846F) COMCTL32.DLL
(000A77FB) COMCTL32.DLL
(000F320C) COMCTL32.DLL
(0001AE85) COMCTL32.DLL
(000152F7) USER32.dll
(00015D35) USER32.dll
(0001FD3A) USER32.dll
(0001FD60) USER32.dll.CallWindowProcW
(00257D96)
(00257C85)
(0028EC2A)
(0037BC78)
(000152F7) USER32.dll
(00015D35) USER32.dll
(0001FD3A) USER32.dll
(0001FD60) USER32.dll.CallWindowProcW
(0043DE5F)
(0037BC78)
(000152F7) USER32.dll
(00015D35) USER32.dll
(000167BF) USER32.dll
(00016885) USER32.dll.DispatchMessageW

Status: unknown_rel_addr

I know how to reproduce the problem or the problem happens frequently enough. I wish to be contacted by the WinSCP team to help resolving the problem.