<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 5.13.7

Error message:
Ошибка доступа к памяти.

Трассировка стека:
(00654CF3) _freebn
(008BF00E) C5105_0
(008C1076) ____ExceptionHandler
(008BDE30) __ExceptionHandler
(0007E16F) ntdll.dll
(0006BD81) ntdll.dll.KiUserExceptionDispatcher
(0065FA93) _ec_public
(0064B7AA) _ssh_agent_forwarding_permitted
(006510FF) _sshfwd_x11_is_local
(00651487) _sshfwd_x11_is_local
(006446A2) C2486_0
(00644855) C2486_0
(00644B70) _ssh_connshare_log
(00673CDD) _select_result
(0073A446) TSecureShell::HandleNetworkEvents
(0073A70A) TSecureShell::ProcessNetworkEvents
(00739CF3) TSecureShell::WaitForData
(00734E85) TSecureShell::Init
(0073475A) TSecureShell::Open
(0077EE2F) TSFTPFileSystem::Open
(007B8F9F) TTerminal::Reopen
(006F3BBD) TTerminalThread::TerminalReopenEvent
(006EEBC4) TSignalThread::Execute
(000A3CDB) Userinterface::C20_0
(00017482) KERNEL32.DLL.BaseThreadInitThunk
(00062AB6) ntdll.dll.RtlAreBitsSet
(00062A83) ntdll.dll.RtlAreBitsSet

(008BF679) C5105_0
(008C0C53) _ReThrowException
(00734F93) TSecureShell::Init
(0073475A) TSecureShell::Open
(0077EE2F) TSFTPFileSystem::Open
(007B8F9F) TTerminal::Reopen
(006F3BBD) TTerminalThread::TerminalReopenEvent
(006EEBC4) TSignalThread::Execute
(000A3CDB) Userinterface::C20_0
(00017482) KERNEL32.DLL.BaseThreadInitThunk
(00062AB6) ntdll.dll.RtlAreBitsSet
(00062A83) ntdll.dll.RtlAreBitsSet

(008BF679) C5105_0
(008C0C53) _ReThrowException
(0073502E) TSecureShell::Init
(0073475A) TSecureShell::Open
(0077EE2F) TSFTPFileSystem::Open
(007B8F9F) TTerminal::Reopen
(006F3BBD) TTerminalThread::TerminalReopenEvent
(006EEBC4) TSignalThread::Execute
(000A3CDB) Userinterface::C20_0
(00017482) KERNEL32.DLL.BaseThreadInitThunk
(00062AB6) ntdll.dll.RtlAreBitsSet
(00062A83) ntdll.dll.RtlAreBitsSet

(008BF679) C5105_0
(008C0C53) _ReThrowException
(00734848) TSecureShell::Open
(0077EE2F) TSFTPFileSystem::Open
(007B8F9F) TTerminal::Reopen
(006F3BBD) TTerminalThread::TerminalReopenEvent
(006EEBC4) TSignalThread::Execute
(000A3CDB) Userinterface::C20_0
(00017482) KERNEL32.DLL.BaseThreadInitThunk
(00062AB6) ntdll.dll.RtlAreBitsSet
(00062A83) ntdll.dll.RtlAreBitsSet

(008BF679) C5105_0
(008C0C53) _ReThrowException
(007B7861) TTerminal::Open
(007B8F9F) TTerminal::Reopen
(006F3BBD) TTerminalThread::TerminalReopenEvent
(006EEBC4) TSignalThread::Execute
(000A3CDB) Userinterface::C20_0
(00017482) KERNEL32.DLL.BaseThreadInitThunk
(00062AB6) ntdll.dll.RtlAreBitsSet
(00062A83) ntdll.dll.RtlAreBitsSet

The problem happens rarely. I cannot reproduce it.

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.

I just issued a console command from my windows pc to the device I used WinSCP and this happens.
-> shutdown -r -F +2

WinSCP 5.9.2

Error message:
Invalid access to memory.

Stack trace:
(003E0AA7) System::SysFreeMem
(00863846) C5073_3
(008658AE) ____ExceptionHandler
(00862668) __ExceptionHandler
(00002275) ntdll.dll.RtlConvertUlongToLargeInteger
(0000D465) ntdll.dll.KiUserExceptionDispatcher
(0085127B) _free
(00614DA7) _safefree
(0062C67E) _freebn
(006372D7) _ec_public
(00623268) _ssh_agent_forwarding_permitted
(00628A8F) _sshfwd_x11_is_local
(00628E17) _sshfwd_x11_is_local
(0061C1DE) C2447_0
(0061C391) C2447_0
(0061C6AC) _ssh_connshare_log
(0064B0C9) _select_result
(006FC5B7) TSecureShell::HandleNetworkEvents
(006FC87A) TSecureShell::ProcessNetworkEvents
(006FBE6B) TSecureShell::WaitForData
(006F7275) TSecureShell::Init
(006F6B4A) TSecureShell::Open
(007348FB) TSFTPFileSystem::Open
(0076F49F) TTerminal::Reopen
(006C6A2D) TTerminalThread::TerminalReopenEvent
(006C19F4) TSignalThread::Execute
(000987A7) Userinterface::C20_0
(0000A710) kernel32.dll

(00863EB1) C5073_3
(0086548B) _ReThrowException
(006F7383) TSecureShell::Init
(006F6B4A) TSecureShell::Open
(007348FB) TSFTPFileSystem::Open
(0076F49F) TTerminal::Reopen
(006C6A2D) TTerminalThread::TerminalReopenEvent
(006C19F4) TSignalThread::Execute
(000987A7) Userinterface::C20_0
(0000A710) kernel32.dll
Authentication failed.

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.