<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 5.9.3

Error message:
Während des Protokollierens ist ein Fehler aufgetreten. Das Protokollieren wurde abgeschaltet.

Out of memory

Stack trace:
(003E7954)
(003E7954)
(003E7A85)
(0035A117)
(0072B4DC)
(0072B61C)
(006AAF52)
(0069758F)
(006A8C54)
(006A8EDF)
(006A8FCB)
(006A9024)
(0069B7A4)
(0069B9DC)
(0076EEFF)
(0008EE20)
(00016C9F)
(0003CF87)
(0003CF44)
(00373100)
(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.