Error changing directory to '/var/www/vhosts/lazarski.pl/lazstrona.lazarski.pl' - _conf_set_filename

<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 5.9.6

Error message:
Error changing directory to '/var/www/vhosts/lazarski.pl/lazstrona.lazarski.pl'.

Invalid access to memory.

Stack trace:
(0062C82F) _conf_set_filename <addr edited>
(008689AA) __odtbl__ TMasterPasswordDialog::Execute
(0086AA12) _WinConfiguration
(008677CC) Userinterface::D21_1
(00081D0F) ntdll.dll
(0006F88A) ntdll.dll.KiUserExceptionDispatcher
(0062C98F) _conf_serialise
(006FFB4E) TSessionData::ImportFromFilezilla
(006FE247) TSessionData::Save
(0073A561) TSFTPFileSystem::SFTPSource
(0073E51D) TSFTPFileSystem::SFTPOpenRemoteFile
(0073EB56) TSFTPFileSystem::SFTPOpenRemote
(0073F28E) TSFTPFileSystem::SFTPCloseRemote
(0074D4E9) TTerminal::OpenTunnel
(0077FCBA) TCopyParamsFrame::UpdateRightsByStr
(0065B6CE) _retrieve_host_key
(0028628A) System::Generics::Collections::TList__1<void __closure
(0040CDDD) Tb2dock::_16664
(0024F5A1) Vcl::Comctrls::TTrackBar::CreateWnd
(00286546) System::Generics::Collections::TList__1<void __closure
(0024F707) Vcl::Comctrls::TTrackBar::CNVScroll
(0024F5A1) Vcl::Comctrls::TTrackBar::CreateWnd
(0024EBE8) Vcl::Comctrls::TCustomTreeView::SetMultiSelect
(00373564) __tpdsc__ System::Generics::Defaults::TComparison__1<System::Generics::Collections::TPair__2<unsigned short, System::Dateutils::TLocalTimeZone::TYearlyChanges *> >
(0002C2B1) USER32.dll
(0000D885) USER32.dll
(0000D4BB) USER32.dll
(00017B07) USER32.dll
(0006F864) ntdll.dll.KiUserCallbackDispatcher
(0000FBFB) USER32.dll.SendMessageW
(000638A8)

The problem happens rarely. I cannot reproduce it.