<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 5.19.5

Error message:
Out of memory

Stack trace:
(0043E03C)
(0043E03C)
(0043E16D)
(0027E4F7)
(0027E642)
(0027EAA2)
(002ADD45)

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.