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 6.3.5

Error message:
Invalid access to memory.

Stack trace:
(002A5DE8)
(00E24572)
(00E265DA)
(00E23394)
(00087F7F) ntdll.dll
(00074501) ntdll.dll.KiUserExceptionDispatcher
(0011C0F6)
(000031E3)
(00E222D5)
(0006709C) ntdll.dll.RtlGetAppContainerNamedObjectPath
(00067069) ntdll.dll.RtlGetAppContainerNamedObjectPath

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.