<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 5.19.6

Error message:
Invalid access to memory.

Stack trace:
(00D04594) TRemoteDirectoryChangesCache::ClearDirectoryChange
(00097AFF) ntdll.dll
(00076021) ntdll.dll.KiUserExceptionDispatcher
(00DCC69E) TTerminal::ReloadDirectory
(00C6D88B) TUnixDirView::ReloadDirectory
(00019228) TCustomScpExplorerForm::Idle
(0004CB4F) TNonVisualDataModule::DoIdle
(0004CB0C) TNonVisualDataModule::SessionIdleTimerTimer
(003C7B64) System::Classes::_18201
(00046CE0) USER32.dll
(00026195) USER32.dll
(00024AC3) USER32.dll
(000245FB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.