Invalid access to memory - _freetree234

Tried to run a shell script on the command line.

WinSCP 5.11.3

Error message:
Invalid access to memory.

Stack trace:
(0065FCF7) _freetree234
(0089D34A) C5067_0
(0089F3B2) ____ExceptionHandler
(0089C16C) __ExceptionHandler
(00088D1F) ntdll.dll
(0006FC11) ntdll.dll.KiUserExceptionDispatcher
(00660B26) _delpos234
(00642BC3) _sshfwd_x11_is_local
(0071A068) TSecureShell::FreeBackend
(00712F88) TSecureShell::~TSecureShell
(0075A540) TSFTPFileSystem::~TSFTPFileSystem
(007955F7) TTerminal::~TTerminal
(000924FE) TManagedTerminal::~TManagedTerminal
(00093A64) TTerminalManager::FreeTerminal
(000930D3) TTerminalManager::FreeActiveTerminal
(0009380E) TTerminalManager::ReconnectActiveTerminal
(000A205A) ShowExtendedExceptionEx
(0001D36C) TCustomScpExplorerForm::ShowExtendedException
(00094D09) TTerminalManager::TerminalShowExtendedException
(0079A090) TTerminal::ShowExtendedException
(0021BC12) Vcl::Forms::TApplication::HandleException
(0037BCBC) System::Classes::_18201
(0001D0B9) USER32.dll
(00027844) USER32.dll
(0002A140) USER32.dll
(000180D7) USER32.dll
(00017C1B) USER32.dll.DispatchMessag

The problem happens rarely. I cannot reproduce it.

Connections time out to the server or it becomes unresponsive then WinSCP crashes

WinSCP 5.15

Error message:
Invalid access to memory.

Stack trace:
(006C1227) _freetree234
(00085B2F) ntdll.dll
(00073A61) ntdll.dll.KiUserExceptionDispatcher
(006C2056) _delpos234
(006A4033) _sshfwd_x11_is_local
(007931D4) TSecureShell::FreeBackend
(0078C018) TSecureShell::~TSecureShell
(007DA104) TSFTPFileSystem::~TSFTPFileSystem
(00810BEF) TTerminal::~TTerminal
(000AA00A) TManagedTerminal::~TManagedTerminal
(000AB6B1) TTerminalManager::FreeTerminal
(000AAB8B) TTerminalManager::FreeActiveTerminal
(00021048) TCustomScpExplorerForm::ShowExtendedException
(000AC985) TTerminalManager::TerminalShowExtendedException
(0081598C) TTerminal::ShowExtendedException
(0023C752) Vcl::Forms::TApplication::HandleException
(003A346C) System::Classes::_18201
(000324B9) USER32.dll
(0002490E) USER32.dll
(0002429D) USER32.dll
(0002406B) USER32.dll.DispatchMessageW

I know how to reproduce the problem or the problem happens frequently enough. I wish to be contacted by the WinSCP team to help resolving the problem.

Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.