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.

<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 5.13.2

Error message:
Class TTB not found

Stack trace:
(0035DBCD) System::Classes::_17009
(00372A81) System::Classes::TReader::FindComponentClass
(00370858) System::Classes::TReader::ReadComponent
(00370B09) System::Classes::TReader::ReadDataInner
(00370A77) System::Classes::TReader::ReadData
(0037E639) System::Classes::TComponent::ReadState
(00370B09) System::Classes::TReader::ReadDataInner
(00370A77) System::Classes::TReader::ReadData
(0037E639) System::Classes::TComponent::ReadState
(00370B09) System::Classes::TReader::ReadDataInner
(00370A48) System::Classes::TReader::ReadData
(0037E639) System::Classes::TComponent::ReadState
(0036B8EE) System::Classes::TStream::ReadComponent
(00361333) System::Classes::_17089
(00362C87) System::Classes::_17116
(00362D15) System::Classes::InitInheritedComponent
(0037FC40) System::Classes::TDataModule::TDataModule
(00033246) TNonVisualDataModule::TNonVisualDataModule
(000E2024) Execute
(000024B4) wWinMain
(008BA679) C4972_0
(00064D85) ntdll.dll.RtlGetAppContainerNamedObjectPath
(00064D52) ntdll.dll.RtlGetAppContainerNamedObjectPath

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.