<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 5.7.1

Error message:
Division by zero

Stack trace:
[01A27ECB]
[01BC1962]
[01BC39CA]
[01BC0944]
[77237186] ntdll.dll.RtlRaiseStatus
[77237012] ntdll.dll.KiUserExceptionDispatcher
[01458D0A]
[01AED571]
[01A27FA3]
[01A27D04]
[01AF37A9]
[01AF63F4]
[01B018DD]
[013FD68B]
[0142024F]
[017C8B3B]
[017C4748]
[017B9B3A]
[017DF3EB]
[01720708]
[757FC4E4] USER32.dll
[757FC5E2] USER32.dll
[757FCC14] USER32.dll
[757FCC6B] USER32.dll.DispatchMessageW

[01BC1FCD]
[01BC35A7]
[01A27DF8]
[01A27D04]
[01AF37A9]
[01AF63F4]
[01B018DD]
[013FD68B]
[0142024F]
[017C8B3B]
[017C4748]
[017B9B3A]
[017DF3EB]
[01720708]
[757FC4E4] USER32.dll
[757FC5E2] USER32.dll
[757FCC14] USER32.dll
[757FCC6B] USER32.dll.DispatchMessageW

[01BC1FCD]
[01BC35A7]
[01AF3AC0]
[01AF63F4]
[01B018DD]
[013FD68B]
[0142024F]
[017C8B3B]
[017C4748]
[017B9B3A]
[017DF3EB]
[01720708]
[757FC4E4] USER32.dll
[757FC5E2] USER32.dll
[757FCC14] USER32.dll
[757FCC6B] USER32.dll.DispatchMessageW

Status: symbol_unknown

The problem happens rarely. I cannot reproduce it.