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 5.17.9

Error message:
Invalid access to memory.

Stack trace:
(00CBF06C)
(000861AF) ntdll.dll
(00072B31) ntdll.dll.KiUserExceptionDispatcher
(00019504)
(000195AE)
(0027ACF1)
(0027A338)
(003A5954)
(0003DF69) USER32.dll
(00034EF5) USER32.dll
(000345D2) USER32.dll
(00032766) USER32.dll.CallWindowProcW
(0047CC8B)
(003A5954)
(0003DF69) USER32.dll
(00034EF5) USER32.dll
(00032C55) USER32.dll
(00032A1B) USER32.dll.DispatchMessageW

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.