<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 5.15.1

Error message:
Invalid access to memory.

Stack trace:
(00352EF8) System::Internal::Strhlpr::UnicodeAssign
(0092636E) C5153_3
(009283D6) ____ExceptionHandler
(00925190) __ExceptionHandler
(0007E19F) ntdll.dll
(0006BD81) ntdll.dll.KiUserExceptionDispatcher
(0075B762) TRemoteFileList::GetParentPath
(0075B029) TRemoteFile::GetFullFileName
(0081F8B2) TTerminal::DoCalculateFileSize
(0081CFC3) TTerminal::ProcessFiles
(008202EA) TTerminal::CalculateFilesSize
(00830A12) TTerminal::CopyToLocal
(0074D999) TDownloadQueueItem::DoTransferExecute
(0074BD5E) TQueueItem::Execute
(0074AD92) TTerminalItem::ProcessEvent
(00749128) TSignalThread::Execute
(000BB14B) Userinterface::C20_0
(00017492) KERNEL32.DLL.BaseThreadInitThunk
(000631C6) ntdll.dll.RtlAreBitsSet
(00063193) ntdll.dll.RtlAreBitsSet

(00352EF8) System::Internal::Strhlpr::UnicodeAssign
(0092636E) C5153_3
(009283D6) ____ExceptionHandler
(00925190) __ExceptionHandler
(0007E19F) ntdll.dll
(0006BD81) ntdll.dll.KiUserExceptionDispatcher
(0075B762) TRemoteFileList::GetParentPath
(0075B029) TRemoteFile::GetFullFileName
(0081F8B2) TTerminal::DoCalculateFileSize
(0081CFC3) TTerminal::ProcessFiles
(008202EA) TTerminal::CalculateFilesSize
(00830A12) TTerminal::CopyToLocal
(0074D999) TDownloadQueueItem::DoTransferExecute
(0074BD5E) TQueueItem::Execute
(0074AD92) TTerminalItem::ProcessEvent
(00749128) TSignalThread::Execute
(000BB14B) Userinterface::C20_0
(00017492) KERNEL32.DLL.BaseThreadInitThunk
(000631C6) ntdll.dll.RtlAreBitsSet
(00063193) ntdll.dll.RtlAreBitsSet

(009269D9) C5153_3
(00927FB3) _ReThrowException
(0081D1D5) TTerminal::ProcessFiles
(008202EA) TTerminal::CalculateFilesSize
(00830A12) TTerminal::CopyToLocal
(0074D999) TDownloadQueueItem::DoTransferExecute
(0074BD5E) TQueueItem::Execute
(0074AD92) TTerminalItem::ProcessEvent
(00749128) TSignalThread::Execute
(000BB14B) Userinterface::C20_0
(00017492) KERNEL32.DLL.BaseThreadInitThunk
(000631C6) ntdll.dll.RtlAreBitsSet
(00063193) ntdll.dll.RtlAreBitsSet

The problem happens rarely. I cannot reproduce it.

<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 5.9.3

Error message:
Invalid access to memory.

Stack trace:
(00323FF0) System::Internal::Strhlpr::UnicodeAssign
(00866422) C5073_3
(0086848A) ____ExceptionHandler
(00865244) __ExceptionHandler
(00081D3F) ntdll.dll
(0006F8EA) ntdll.dll.KiUserExceptionDispatcher
(006D412E) TRemoteFileList::GetParentPath
(006D3A05) TRemoteFile::GetFullFileName
(0077B58C) TTerminal::CalculateFileSize
(00778FBD) TTerminal::ProcessFiles
(0077B9EA) TTerminal::CalculateFilesSize
(00787735) TTerminal::CopyToLocal
(006C831F) TDownloadQueueItem::DoExecute
(006C551E) TTerminalItem::ProcessEvent
(006C39C4) TSignalThread::Execute
(00098AD3) Userinterface::C20_0
(000152C2) KERNEL32.DLL.BaseThreadInitThunk
(0005FFD7) ntdll.dll
(0005FF9F) ntdll.dll

(00323FF0) System::Internal::Strhlpr::UnicodeAssign
(00866422) C5073_3
(0086848A) ____ExceptionHandler
(00865244) __ExceptionHandler
(00081D3F) ntdll.dll
(0006F8EA) ntdll.dll.KiUserExceptionDispatcher
(006D412E) TRemoteFileList::GetParentPath
(006D3A05) TRemoteFile::GetFullFileName
(0077B58C) TTerminal::CalculateFileSize
(00778FBD) TTerminal::ProcessFiles
(0077B9EA) TTerminal::CalculateFilesSize
(00787735) TTerminal::CopyToLocal
(006C831F) TDownloadQueueItem::DoExecute
(006C551E) TTerminalItem::ProcessEvent
(006C39C4) TSignalThread::Execute
(00098AD3) Userinterface::C20_0
(000152C2) KERNEL32.DLL.BaseThreadInitThunk
(0005FFD7) ntdll.dll
(0005FF9F) ntdll.dll

(00866A8D) C5073_3
(00868067) _ReThrowException
(007

The problem happens rarely. I cannot reproduce it.