Invalid access to memory

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.9.5

Error message:
Invalid access to memory.

Stack trace:
(0041CFD7)
(000851CF) ntdll.dll
(00073161) ntdll.dll.KiUserExceptionDispatcher
(0040CF21)
(00225D1B)
(0037326C)
(00031B59) USER32.dll
(000240EE) USER32.dll
(00023A7D) USER32.dll
(0002384B) USER32.dll.DispatchMessageW

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.