<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 6.7

Error message:
Integer overflow

Stack trace:
(0040CE63)
(001698DA) System::Error
(0016CCE3) System::UStrFromPWCharLen
(003C8ABA) Vcl::Controls::TControl::GetText
(0040AF24) Vcl::Stdactns::TEditSelectAll::UpdateTarget
(00234047) System::Classes::TComponent::UpdateAction
(004D90B3) Vcl::Forms::_16868
(004D9174) Vcl::Forms::TCustomForm::CMActionUpdate
(003CA36A) Vcl::Controls::TControl::WndProc
(0016B1B7) System::TObject::Dispatch
(00B3BC80) TEditorRichEdit::Dispatch
(003CA36A) Vcl::Controls::TControl::WndProc
(000274E5) USER32.dll
(003CF61D) Vcl::Controls::TWinControl::DefaultHandler
(0016EDEE) System::FinalizeArray
(003EF817) Vcl::Stdctrls::TCustomEdit::DefaultHandler
(0016B1B7) System::TObject::Dispatch
(003CF515) Vcl::Controls::TWinControl::WndProc
(003CA36A) Vcl::Controls::TControl::WndProc
(004D36EC) Vcl::Forms::TCustomForm::WndProc
(0016B8F6) System::TMonitor::Exit
(0016B952) System::TMonitor::Exit
(00BD68E3) C4923_0
(003CEA20) Vcl::Controls::TWinControl::MainWndProc
(003CEA35) Vcl::Controls::TWinControl::MainWndProc
(000382E7) ntdll.dll
(00235394) System::Classes::_18364
(00038CC1) USER32.dll
(00027D78) USER32.dll
(00027E82) USER32.dll
(00027E12) USER32.dll
(00027A63) USER32.dll
(00027E79) USER32.dll
(0016B5D0) System::TMonitor::CheckOwningThread
(003AFE6D) Vcl::Graphics::FreeMemoryContexts
(003C9FA0) Vcl::Controls::TControl::Perform
(004DF93F) Vcl::Forms::TApplication::DispatchAction
(004DCE4D) Vcl::Forms::TApplication::WndProc
(000382E7) ntdll.dll
(00235394) System::Classes::_18364
(00038CC1) USER32.dll
(00027D78) USER32.dll
(00027A63) USER32.dll
(000290ED) USER32.dll
(0002781B) USER32.dll
(000329D7) USER32.dll
(00079604) ntdll.dll
(000001EA) win32u.dll
(000290BB) USER32.dll
(00040403) USER32.dll
(00027541) USER32.dll
(003C4F18) Vcl::Controls::SendAppMessage
(003B6DD6) Vcl::Actnlist::TCustomAction::Update
(00234404) System::Classes::TBasicActionLink::Update
(00576613) Tb2item::TTBCustomItem::InitiateAction
(0057A262) Tb2item::TTBView::InitiateActions
(00584709) Tb2toolbar::TTBCustomToolbar::InitiateAction
(004D8E32) Vcl::Forms::_16859
(004D8E5A) Vcl::Forms::_16859
(004D8ECB) Vcl::Forms::TCustomForm::UpdateActions
(004DE922) Vcl::Forms::TApplication::DoActionIdle
(004DEA70) Vcl::Forms::TApplication::Idle
(004DDAD7) Vcl::Forms::TApplication::HandleMessage
(004DDE09) Vcl::Forms::TApplication::Run
(0015C27B) Execute
(0002809F) ntdll.dll
(0002A7A1) USER32.dll
(0002A77C) USER32.dll
(000AFFA8) ntdll.dll
(004DC941) Vcl::Forms::_17039
(004DD1A7) Vcl::Forms::TApplication::WndProc
(00027E82) USER32.dll
(00027E12) USER32.dll
(00027A63) USER32.dll
(00027E79) USER32.dll
(0001578E) KERNEL32.DLL
(00028F04) USER32.dll
(000048E7) wWinMain
(0016329C) __AfterConstruction
(0

The problem happens rarely. I cannot reproduce it.