<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 was trying to download 3 million files then this happen.

WinSCP 5.13

Error message:
Out of memory

Stack trace:
(003F0EEE)
(003F0EEE)
(003CBFA1)
(003CA29B)
(00034422)
(003C0F10)
(001A6CA6)
(00218B0E)
(00218B0E)
(00218B8C)

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.