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.)>
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WinSCP 5.9.5

Error message:
Invalid access to memory.

Stack trace:
(00866A8A)
(000420BE) ntdll.dll.RtlRaiseStatus
(00041F26) ntdll.dll.KiUserExceptionDispatcher
(00061F4A)
(00010FDF)
(003B5440)
(0019C56E)
(0020E3D6)
(0020E454)

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.