External exception EEFFACE

<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)>
trying to synchronize big directories !remote! mode


WinSCP 5.9.2

Error message:
External exception EEFFACE

Stack trace:
(000D96F2) KERNELBASE.dll.RaiseException
(0008147F) ntdll.dll
(0006F02A) ntdll.dll.KiUserExceptionDispatcher
(004B8B7C)
(0086409A)
(0086548B)
(0077F0F1)
(000190CD)
(00042755)
(0003B241)
(003B4D08)
(0019BE81)
(00372BEC)
(0002C2B1) USER32.dll
(0000D885) USER32.dll
(0000D1DF) USER32.dll
(0000CF9B) USER32.dll.DispatchMessageW

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.