<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 5.7.7

Error message:
Zugriffsverletzung - ungültiger Zugriff auf den Speicher.

Stack trace:
(007E08AA) C4799_0
(007E2912) ____ExceptionHandler
(007DF88C) __ExceptionHandler
(00002275) ntdll.dll.RtlConvertUlongToLargeInteger
(0000D485) ntdll.dll.KiUserExceptionDispatcher
(000A9A85) Execute
(00002462) wWinMain
(007DEA01) C4667_0

(003B1948) System::HandleAnyException
(007E08AA) C4799_0
(007E2912) ____ExceptionHandler
(007DF88C) __ExceptionHandler
(00002275) ntdll.dll.RtlConvertUlongToLargeInteger
(0000D485) ntdll.dll.KiUserExceptionDispatcher
(000A9A85) Execute
(00002462) wWinMain
(007DEA01) C4667_0

The problem happens rarely. I cannot reproduce it.