This bug has been added to the tracker:
https://winscp.net/tracker/1808

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.)>

Trying to synchronize local and remote directories.

<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.16.1

Error message:
Division by zero

Stack trace:
(00E3BA8C) TSynchronizeProgressForm::CalculateProgress
(0008402F) ntdll.dll
(00071931) ntdll.dll.KiUserExceptionDispatcher
(00E3B938) TSynchronizeProgressForm::Start
(0001DF3F) TCustomScpExplorerForm::DoFullSynchronizeDirectories
(0004FC46) TScpCommanderForm::FullSynchronizeDirectories
(00047B78) TNonVisualDataModule::ExplorerActionsExecute
(003E7AB8) System::Actions::TContainedActionList::ExecuteAction
(001C66A1) Vcl::Actnlist::TCustomAction::Execute
(003A4094) System::Classes::_18201
(00045249) USER32.dll
(000364D7) USER32.dll
(00035616) USER32.dll
(000353EB) USER32.dll.DispatchMessageW

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.

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)>

I give the Synchronize command.
It get this error message.


WinSCP 5.16

Error message:
Division by zero

Stack trace:
(00E337B8) TSynchronizeProgressForm::CalculateProgress
(0006248E) ntdll.dll
(0000F15E) ntdll.dll.KiUserExceptionDispatcher
(00E33664) TSynchronizeProgressForm::Start
(0001DF37) TCustomScpExplorerForm::DoFullSynchronizeDirectories
(0004FC26) TScpCommanderForm::FullSynchronizeDirectories
(00047B58) TNonVisualDataModule::ExplorerActionsExecute
(003E7CB8) System::Actions::TContainedActionList::ExecuteAction
(001C68A1) Vcl::Actnlist::TCustomAction::Execute
(003A4294) System::Classes::_18201
(00015307) USER32.dll
(00015D45) USER32.dll
(000167D2) USER32.dll
(00016895) USER32.dll.DispatchMessageW

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.