<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 5.17.6

Error message:
Invalid access to memory.

Stack trace:
(0027CC7F)
(00087E3F) ntdll.dll
(000732D1) ntdll.dll.KiUserExceptionDispatcher
(0044BC05)
(0044BC05)
(0044BC05)
(0044BC94)
(0045E3CA)
(0044B925)
(002508EF)
(003A4AC8)
(000434B9) USER32.dll
(00023FF7) USER32.dll
(00023149) USER32.dll
(00022F2B) USER32.dll.DispatchMessageW

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.