Invalid access to memory

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WinSCP 5.21.5

Error message:
Invalid access to memory.

Stack trace:
(0043CEF8) System::HandleAnyException
(00097F5F) ntdll.dll
(00076171) ntdll.dll.KiUserExceptionDispatcher
(003C9C0C) System::Classes::_18201
(00046D70) USER32.dll
(00026125) USER32.dll
(00024A53) USER32.dll
(0002458B) USER32.dll.DispatchMessageW

Status: all_insignificant

The problem happens rarely. I cannot reproduce it.