Range check error

<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 5.9.1

Error message:
Range check error

Stack trace:
(003E7135)
(003E7135)
(003E7315)
(0039C421)
(0039C3CC)
(006722BA)
(000A06F6)
(006820F6)
(006822D7)
(0086076D)
(00038880) ntdll.dll
(00038850) ntdll.dll

Status: unknown_rel_addr

I click on winscp.exe and the message Range check error appears.

The problem happens rarely. I cannot reproduce it.