<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 5.17.1

Error message:
Error reading TBXItem13.GroupIndex: Property GroupIndex does not exist

Трассировка стека:
(0039346F) System::Classes::_17619
(00394D29) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394B83) System::Classes::TReader::ReadComponent
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394B83) System::Classes::TReader::ReadComponent
(00394D9D) System::Classes::TReader::ReadDataInner
(00394CDC) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00232DB9) Vcl::Forms::TCustomForm::ReadState
(00395CB7) System::Classes::TReader::ReadRootComponent
(0038FB82) System::Classes::TStream::ReadComponent
(003855C7) System::Classes::_17089
(00386F1B) System::Classes::_17116
(00386FA9) System::Classes::InitInheritedComponent
(002325B2) Vcl::Forms::TCustomForm::TCustomForm
(0000448A) Vcl::Forms::TForm::TForm
(00003B0D) TCustomScpExplorerForm::TCustomScpExplorerForm
(0004CB06) TScpCommanderForm::TScpCommanderForm
(0023D562) Vcl::Forms::TApplication::CreateForm
(00E4343F) _SafeFormCreate
(00002658) wWinMain
(00F82E7D) __wstartup
(00066B72) ntdll.dll.RtlGetAppContainerNamedObjectPath
(00066B3F) ntdll.dll.RtlGetAppContainerNamedObjectPath

(003952FB) System::Classes::_17687
(00395535) System::Classes::TReader::ReadProperty
(00394D29) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394B83) System::Classes::TReader::ReadComponent
(00394D9D) System::Classes::TReader::ReadDataInner
(00394D0B) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00394B83) System::Classes::TReader::ReadComponent
(00394D9D) System::Classes::TReader::ReadDataInner
(00394CDC) System::Classes::TReader::ReadData
(003A2985) System::Classes::TComponent::ReadState
(00232DB9) Vcl::Forms::TCustomForm::ReadState
(00395CB7) System::Classes::TReader::ReadRootComponent
(0038FB82) System::Classes::TStream::ReadComponent
(003855C7) System::Classes::_17089
(00386F1B) System::Classes::_17116
(00386FA9) System::Classes::InitInheritedComponent
(002325B2) Vcl::Forms::TCustomForm::TCustomForm
(0000448A) Vcl::Forms::TForm::TForm
(00003B0D) TCustomScpExplorerForm::TCustomScpExplorerForm
(0004CB06) TScpCommanderForm::TScpCommanderForm
(0023D562) Vcl::Forms::TApplication::CreateForm
(00E4343F) _SafeFormCreate
(00002658) wWinMain
(00F82E7D) __wstartup
(00066B72) ntdll.dll.RtlGetAppContainerNamedObjectPath
(00066B3F) ntdll.dll.RtlGetAppContainerNamedObjectPath

The problem happens rarely. I cannot reproduce it.